Advanced Materials Synthesis, Processing and CharacterizationCC
Laser and plasma processing for advanced applications in material science
Laser and plasma sources are crucial for a large variety of applications in micro- and nano-science and technology in fields ranging from materials science to biomedicine. The proposed symposium provides an interdisciplinary forum for discussing the most recent progress in laser processing of materials, specifically for laser/plasma-assisted synthesis, diagnostics, and advanced applications.
The proposed symposium addresses the field of laser materials processing and laser-matter interaction, including laser- and plasma-based materials synthesis, surface structuring and functionalization, process analytics and materials diagnostics with the special emphasis on the micro- and nano-scale. The symposium includes fundamental and applied topics and is bridging the wide range between science and technology.
Laser ablation, patterning, micro-/nano- structuring, microanalysis and laser-based synthesis of nanomaterials of materials are widely applied across the full range of scientific disciplines, covering materials science, engineering, photonics, biophotonics, display technologies and opto- and micro-electronics for biosensing and environmental monitoring. The recent availability of high-power and ultrashort pulse lasers has also opened up new ‘avenues’ in multiphotonic materials processing, allowing the fabrication of surface nanostructures; sub-surface material modifications inside functional dielectric hosts, time-resolved diagnostics, high-rate and high-precision laser machining, optically-induced transfer, or laser direct write methods for true nanoscale materials engineering.
This symposium will provide a platform to establish interdisciplinary international research collaborations between scientist promoting research in the field of materials research, physics, chemistry, biology and life-science.
The symposium will consist of invited presentations by leading scientists in their respective fields of research and contributed papers for oral and poster presentations. Special emphasis will be made for presentations by young scientists presenting top achievements. The contributions should concern, but are not limited to the topics listed below.
Hot topics to be covered by the symposium:
- Laser 3D micro-structuring for MEMS, MOEMS, photonic crystals and photonic applications;
- Laser Induced Forward Transfer of functional materials for organic electronics and sensing applications;
- Laser assisted fabrication for sensors (bio-, chemical- and environmental-);
- Ultra-short, ultra-high power laser interaction with matter: fundamentals and applications in biology and materials science;
- Laser processing of materials: thin films growth and particle production;
- Subwavelength laser produced structures for smart optical, electro-optical, electronic and biological devices;
- Laser-induced nanostructures: from theory to applications;
- Time-resolved diagnostics for laser and plasma processing;
- Multiphoton based processing techniques.
Confirmed invited speakers:
- N. Destouches (University of Lyon, France), "Tuning the photochemistry of silver nanoparticles in TiO2 with a gaussian-shape laser"
- F. Di Pietrantonio (“O.M. Corbino” Institute of Acoustics and Sensors, CNR, Italy), “Fabrication of piezoelectric piezoelectric based chemical and bio-sensors by laser assisted deposition techniques”
- J. Gottmann (RWTH Aachen University), "Digital production of 3D glass parts by high power ultrafast laser and chemical etching"
- C. Guo (University of Rochester, USA), "Black and colored metals and applications"
- A. Pique (Naval Research Laboratory, Washington, USA), "Laser Forward Transfer of Congruent Voxels "
- G. Rijders (Institute for Nanotechnology, University of Twente), "Functional properties of all-oxide piezo MEMS devices"
- J. Siegel (Spanish National Research Council, CSIC, Madrid, Spain), "Femtosecond microscopy: Visualizing ablation dynamics and non-linear propagation of light in dielectrics"
- M. Terakawa (Keio University, Yokohama, Japan), "Enhanced-ultrafast optical field for biomedical applications"
S. Amoruso - CNR-INFM Napoli (Italy), C.B. Arnold - Princeton University (USA), P.A. Atanasov - Institute of Electronics Sofia, C. Boulmer-Leborgne - GREMI Université d'Orléans (France), I.W. Boyd - Sydney Nanostructures Center (Australia), N.M. Bulgakova - Institute of Thermophysics SB-RAS (Russia), C. Champeaux - Université de Limoges (France), B. Chichkov, Laser Zentrum Hannover (Germany), G. Compagnini - Universita di Catania (Italy), F. Costache - Fraunhofer Institute for Photonic Micro-systems (Germany), V. Craciun - University of Florida (USA), M. Dinescu - National Institute for Laser Plasma and Radiation Physics (Romania), R. Eason - University of Southampton (UK), Q. Feng - Univ. of Science and Technology Beijing (China), E. Fogarassi - ENSPS Strasbourg (France), F. Garellie - Université Jean Monet Saint Etienne (France), H. Fukumura - Tohoku University (Japan), D. Geohegan, Oak Ridge (USA), H. Helvajian - Aerospace Corp. (USA), J. Krüger - BAM Federal Institute for Materials Research and Testing (Germany), T. Lippert - Paul Scherrer Institute (Switzerland), A. Luches - Universita del Salento (Italy), J.G. Lunney - Trinity College Dublin (Ireland), E. Millon - Université d'Orléans (France), S. Orlando - CNR-IMIP/PZ (Italy), P. Ossi - Politecnico di Milano (Italy), N. Pryds - Risoe National Laboratory (Denmark), J. Perriere - INSP Paris (France), J. Reif - Brandenburg Technical University Cottbus (Germany), M. Pervolaraki - University of Cyprus (Cyprus), J. Schou - Risoe National Laboratory (Denmark), P. Schaaf - Technische Universität Ilmenau (Germany), Georges Shafeev - General Physics Institute, Moscow (Russia), R. Serna, J. Solis - CSIC, Instituto de Optica (Spain), M. Stratakis - FORTH-IESL (Greece), M. Stuke - Max-Planck-Institut für biophysikalische Chemie (Germany), T. Szoreny - Hungarian Academy of Sciences (Hungary), K. Zimmer - IOM Leipzig (Germany)
Selected papers will be published as a special issue of the journal Applied Surface Science (Elsevier).
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Authors : Robert W Eason, Matthias Feinaeugle, Daniel J Heath, James A Grant-Jacob, Ben Mills
Affiliations : Optoelectronics Research Centre, University of Southampton, Highfield, Southampton, SO171BJ, UK
Resume : Laser-induced forward transfer (LIFT) is a technique for depositing pixels from thin film donor materials. During LIFT, a pixel is released from a donor-coated transparent receiver placed in contact or close proximity to a receiver substrate due to the action of the laser pulse/pulses absorbed in a small volume of the donor or auxiliary sacrificial layer. In contrast to forward transfer, if the (transparent) receiver substrate lies in the beam path, pixels can be transferred in the backward direction and the process is then referred to as laser-induced backward transfer (LIBT). If transfer of pixels is required with specific shapes however, then there are two choices: use a fixed aperture to spatially format the incident laser pulse, or use a spatial light modulator to dynamically pattern the spatial profile of the incident laser pulse. In this work we have used a spatial light modulator (a Texas Instruments digital micromirror device, DMD) to adaptively control the incident laser pulse to have spatial profiles such as geometric and alphabetic shapes for both LIFT and LIBT. The clear advantage of using the DMD approach is that pixels of essentially arbitrary shapes can be transferred on a shot-to-shot basis. We have investigated DMD-assisted transfer of a range of materials including glasses, compound semiconductors, silicon and polymers, with the greatest success in terms of shape fidelity and lack of material damage in the case of the latter. Features have been printed via LIFT and LIBT with size scales in the region of tens of microns, and we will present our most recent optimised results and draw conclusions concerning the more widespread use of DMD-assisted materials transfer.
Authors : A. Patrascioiu (1), C. Florian (1), J.M. Fernández-Pradas (1), J.L. Morenza (1), G. Hennig (2), P. Delaporte (3), P. Serra (1)
Affiliations : (1) Departament de Física Aplicada i Optica, Universitat de Barcelona (2) DI Projekt AG (3) Aix Marseille University, CNRS, LP3 UMR 7341
Resume : Laser-induced forward transfer (LIFT) is a versatile, high-resolution printing technique that enables the deposition of a wide range of inks allowing the precise printing of micron-sized droplets through a jetting mechanism triggered by a pulsed laser beam. At low and moderate printing speeds each printing event is initiated only after the completion of the previous droplet. However, current industrial demands require working at such high speeds that can lead to the coexistence of liquid jets generated sequentially during their expansion. Depending on the separation between adjacent jets, the interaction between them is possible; and this can compromise the printing outcome. In this work we use time-resolved imaging to investigate such interaction. In a first experiment droplets were simultaneously printed at different inter-beam separations; the analysis of their morphology revealed that a significant departure from the single-beam dynamics was taking place below a specific separation. In a second experiment, time-resolved images of the jetting dynamics revealed the existence of a significant jet-jet interaction that could explain the observed departure, an interaction that proceeds through remarkable jet deflection, for which a possible onset mechanism is proposed.
Laser processing for advanced applications: MEMS, Lab-on-chip, etc. : N. Scarisoreanu
Authors : Guus Rijnders
Affiliations : MESA+ Institute for Nanotechnology, University of Twente, POBox 217, 7500AE, Enschede, the Netherlands
Resume : Within this contribution, I will focus on the recent progress in the fabrication of all-oxide piezo-MEMS devices by pulsed laser deposition. In our devices, we use Pb(Zr,Ti)O3 (PZT) as the piezoelectric material. The ferro- and piezoelectric properties are strongly related to the crystal orientation as well as the strain state of the PZT layer. Successful integration of these devices into silicon technology is therefore not only dependent on the ability of epitaxial growth on silicon substrates, but also the control of the crystallographic orientation as well as the strain state. We have fabricated all-oxide piezoMEMS devices and studied the resulting properties, such as piezomechanical actuation and sensor properties. I will further highlight the epitaxial growth of oxides on silicon wafers, with special attention on the initial growth of complex oxides on Si. Furthermore, our recent progress on large area deposition by PLD will be presented. Currently, in collaboration with our spin-of partner Solmates BV, we are able to fabricate piezoMEMS devices using a 200 mm technology. Using this technology, biosensors and actuators for use in ink jet printing have been fabricated end characterized. The outcome of these studies will be presented.
Authors : Salvatore Surdo, Simonluca Piazza, Luca Ceseracciu, Alberto Diaspro and Marti Duocastella
Affiliations : Nanophysics Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163, Genova, Italy
Resume : Advances towards the paradigm of lab-on-a-chip (LOC) demand for fabrication methods capable of producing micro- and nanometric features in a rapid and cost effective way. Among existing approaches, soft lithography is particularly suitable for LOC due to its ease of implementation and compatibility with a wide range of materials and substrates. However, this stamp-based strategy is currently limited by the multistep process required for the fabrication of elastomeric stamps, which typically involves expensive photomasks and a clean room facility. Here we propose a mask-free, single-step method for the fabrication of soft lithography stamps based on laser ablation of pre-stretched elastomers. Our approach can be performed in ambient conditions and is not limited by diffraction, providing a resolution enhancement equal to the elongation of the elastomer. In particular, we stretch biaxially a thin film (1 mm) of cured poly(dimethylsiloxane) (PDMS) up to a factor of 5, and we place it in a laser-direct writing system. By focusing and scanning a pulsed laser beam on the PDMS surface, we are able to obtain microstructures according to a desired pattern. After removing the stress applied to the PDMS, the film relaxes to its original size and the microstructures shrink while preserving their shape. This novel method opens up new interesting possibilities for the rapid design of high aspect ratio structures suitable for soft lithography and LOC technologies.
Authors : R. Cristescu1, A. Visan1, G. Dorcioman1, G. Socol1, I.N. Mihailescu1, A.M. Grumezescu2, M.C. Chifiriuc3, R.D. Boehm4, R.J. Narayan4, and D.B. Chrisey5
Affiliations : 1National Institute for Lasers, Plasma & Radiation Physics, 1Lasers Department, P.O. Box MG-36, Bucharest-Magurele, Romania 2Department of Science and Engineering of Oxidic Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, Politehnica University of Bucharest, Bucharest, Romania 3Microbiology Immunology Department, Faculty of Biology, Research Institute of the University of Bucharest - ICUB, 77206 Street, Bucharest, Romania 4Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA 5Department of Physics and Engineering Physics, Tulane University, New Orleans, LA, USA
Resume : Candida species are now emerging as a significant cause of nosocomial infections. In particular, fungal biofilms on medical devices are refractory to many conventional therapies. The aim of this study was to explore the potential of thin films fabricated by matrix assisted pulsed laser evaporation (MAPLE) to release combinations of flavonoids (e.g., quercetin and resveratrol) and systemic antifungals (e.g., amphotericin B and voriconazole) in order to examine a putative synergic antifungal effect of these natural and synthetic substances. Thin films were deposited using a pulsed KrF* excimer laser source and then characterized by Fourier transform infrared spectroscopy and atomic force microscopy. Homogenous uniform thin films with chemical structure similar to dropcast ones were obtained at the optimum laser fluence of ~ 80 mJ/cm2. The bioactive substances were successfully loaded into the polymer thin films. The results of the microbiological analyses involving a modified disk diffusion approach, which involved use of Candida albicans ATCC 90028 and Candida parapsilosis ATCC 22019 strains, revealed release of the antifungal agents in an active form. A slight synergic effect was obtained for quercetin and voriconazole against Candida albicans. The obtained results suggest that the MAPLE-deposited bioactive thin films have significant potential for the design of hybrid drug delivery systems in general and antifungal medical device surfaces in particular.
Authors : A. Palla Papavlu1,2, S. Antohe1, T. Lippert3, M. Dinescu2
Affiliations : 1 Faculty of Physics, University of Bucharest, Magurele, ZIP 077125, Romania 2 Lasers Department, National Institute for Lasers, Plasma, and Radiation Physics, Magurele, MG 16, ZIP 077125, Romania 3 General Energy Research Department, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
Resume : Devices based on the conversion of light into electrical signals, i.e. photodetectors represent the basis for a multitude of applications, including chemical sensing, video imaging, or optical communications. The application of carbon nanotubes (CNTs) and nanowires (CNWs) in photodetectors have already been reported, however, their application in such devices is limited by the complicated fabrication processes and expensive equipment. Therefore, we evaluated laser-induced forward transfer (LIFT) as a new approach to design and fabricate flexible photodetector devices. In LIFT a laser beam is imaged through a transparent support onto the backside of the thin film material to be transferred. Each single laser pulse promotes the transfer of the thin film material onto a receiver that is placed parallel and facing the film. CNTs/CNWs were transferred by LIFT as pixels between indium tin oxide electrodes onto a polyethylene terephthalate substrate. This study is focused on evaluating the performances of the devices fabricated by LIFT under different experimental conditions, i.e. thickness of the pixels between the bridging electrodes, laser fluence, etc.. In addition, the performance of the LIFT-ed photodetectors at a single wavelength is also investigated. Our results indicate that LIFT is a promising technique to fabricate stable and fast responding devices for photodetector applications. Acknowledgement This work was supported by the strategic grant POSDRU/159/1.5/S/137750.
Poster Session CC: Laser- & plasma-assisted deposition and -processing : A. Palla-Papavlu, C. Focsa, N. Semmar
Authors : A. El hat, I. Chaki, M. Rouchdi , A. Mzerd, and M. Abd-Lefdil
Affiliations : University of Mohammed V-Agdal, Faculty of Sciences, Materials Physics Laboratory, B.P. 1014, Rabat, Morocco
Resume : Nanostructured GdxZn1-xO thin films with different Gd concentration from 0% to 4.5% deposited by spray pyrolysis technique on glass substrate at 350°C.The films were characterized by structural, surface, optical and electrical properties, respectively. X-ray diffraction analysis shows that the Gd doped ZnO films hexagonal structure and preferential orientation along (002) plane. Scanning electronic microscopy were used to study the films morphology. Optical analysis of the deposited films show an average optical transmittance of 90% in the visible region; meanwhile the band gap value oscillates around 3.27-3.22eV, with a shift towards higher values when the Gd concentration is decreased. The Hall effect electrical measurements showed that ZnO thin films not doped and have an electrical conductivity doped n-type. The best value of the electrical resistivity is of the order of 2.101 ohm.cm obtained in the layer of doped ZnO 1.5% Gd.
Authors : J. Perrière1,2, C. Hebert1,2, N. Jedrecy1,2, W. Seiler3, O. Zanellato3, X. Portier4, R. Perez-Casero5, E. Millon6, M. Nistor7
Affiliations : 1Sorbonne Universités, UPMC Univ Paris 06, UMR 7588, INSP, 4 Place Jussieu, F-75005 Paris,France ; 2CNRS, UMR 7588, INSP, 4 Place Jussieu, F-75005 Paris, France ; 3PIMM, UMR CNRS 8006 Arts et Métiers ParisTech, 151 Boulevard de lhopital, 75013 Paris, France ; 4CIMAP, CEA/CNRS UMR 6252/ENSICAEN/UCBN, 6 Boulevard du Maréchal Juin, 14050 Caen Cedex, France ; 5Departamento de Fisica Aplicada, Facultad de Ciencas, Universidad Autonoma de Madrid, C/Francisco Tomas y Valiente 7, 28049 Madrid, Spain ; 6Univ Orleans, UMR CNRS 7344, GREMI, 14 Rue Issoudun, F-45067 Orleans 2, France ; 7National Institute for Lasers, Plasma and Radiation Physics, L22 POB MG-36, 77125 Bucharest, Romania.
Resume : Pulsed-laser deposition is known as a well-suited method for growing thin films of oxide compounds presenting a wide range of functional properties. A limitation of this method for industrial process is the very anisotropic expansion dynamics of the plasma plume which induces difficulties to grow on a large scale films with homogeneous thickness and composition. The specific aspect of the crystalline or orientation uniformity has not been investigated, despite its important role on oxide films properties. In this work, the crystalline parameters and the texture of zinc oxide films are studied as a function of position with respect to the central axis of the plasma plume. We demonstrate the existence of large non-uniformities in the films. The stoichiometry, the lattice parameter and the distribution of crystallites orientations drastically depend on the position with respect to the plume axis, i.e. on the oblique incidence of the ablated species. The origin of these non-uniformities, in particular the unexpected tilted orientation of the ZnO c-axis may be attributed to the combined effects of the oblique incidence and of the ratio between oxygen and zinc fluxes reaching the surface of the growing film.
Authors : Stela Canulescu(1), Max D?beli(2), J?rgen Schou(3)
Affiliations : (1) Department of Photonics Engineering, Technical University of Denmark, DK-4000 Roskilde, Denmark (2) Ion Beam Physics, ETH H?nggerberg, Swiss Federal Institute of Technology, CH-8093 Z?rich, Switzerland (3) Department of Photonics Engineering, Technical University of Denmark, DK-4000 Roskilde, Denmark
Resume : The angular distribution of Au and Cu atoms ejected from laser ablation of Au-Cu target in vacuum was studied to examine the degree of congruent transfer in pulsed laser deposition. A multicomponent Au-Cu target containing light and heavy atoms at a comparable atomic ratio (50 at% Cu- 50 at% Au) was irradiated with a Nd:YAG laser at a wavelength of 355 nm using a circular laser beam. The sputtered material was collected on Si substrates placed over a wide range of angles in a symmetrical geometry with respect with normal incidence. The bulk composition of the Au-Cu films was analysed by Rutherford Backscattering Spectrometry (RBS), while the thickness of the films was measured by profilometry and also derived from RBS spectra. Ablation of the Au-Cu target at low fluence (1 J/cm2) results in a congruent transfer for a wide range of angles. At relatively large laser fluence, i.e. 4 J/cm2, the ratio between the Cu to Au atoms deviates significantly from the target stoichiometry, with large depletion of the lighter component (Cu) at angles close to normal incidence. However, the average composition of the films deposited at large angles is similar to that of the target, suggesting that preferential scattering in the plume may play a significant role. To our knowledge, such large deviation in stoichiometry of the lighter component in the laser-deposited films has not been reported earlier, and the possible mechanisms that lead to the significant loss of Cu in the deposited films.
Authors : E. Popovici 1, R. D'Amato 2, E. Dutu 1, A. Badoi 1, L. Gavrila 1
Affiliations : 1. National Institute for Lasers, plasma and Radiation Physics, Romania 2. ENEA ? Frascati Research Centre, Rome, Italy
Resume : This work presents the results obtained by laser pyrolysis synthesis of SiC nanoparticles, when studying the thermal processes occurring following the interaction with laser beam and SiH4/C2H2 precursors, processed by different ways. One of the directions of current research is the study and application of the phenomenon of decomposition of precursors during combustion. There are exposed new control methods as: synthesis flame image analysis, processing of heat maps of the flame, real-time pyrometric monitoring of default synthesis parameters ? in combination of the previous mentioned ones. Analyzes of resulted SiC NP were performed based on investigations SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), XRD (X-ray Diffraction), etc. In domain of SiC nanopowders synthesis by laser pyrolysis, there are proposed new methods of control such as the synthesis flame image analysis combined with real-time pyrometer monitoring of the default synthesis parameters, synthesis of SiC with Si in solid and vapor phase, with preheating of precursors, etc.
Authors : A.Og. Dikovska1, G.B. Atanasova2, G.V. Avdeev3, P.A. Atanasov1
Affiliations : 1Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784, Bulgaria 2Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia, Bulgaria 3Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.11, 1113 Sofia, Bulgaria
Resume : The synthesis of semiconducting nanostructures has attracted considerable interest due to their potential importance in nanodevice fabrication. Among the various growth methods, pulsed laser deposition (PLD) has proved to be a suitable method for the synthesis of nano-scale materials. In this work, ZnO nanostructures were fabricated on noble-metal (Au, Ag and AuxAg1-x alloys) coated silicon substrates by applying pulsed laser deposition. The samples were prepared at substrate temperatures in the range of 450 650 °C, oxygen pressure of 5 Pa, and laser fluence ≤ 1 J cm-2 process parameters usually used for thin-film deposition. The metal layers role is substantial for the preparation of nanostructures.We observed that the increase of the substrate temperature during the heating changed the morphology of the metallayer and, subsequently, nanoparticles were formed.The use of different metal particles resulted in different morphologies and properties of the ZnO nanostructures synthesized.The morphology of the ZnO nanostructures was related to the substrate temperature and the AuxAg1-x alloys content of the pre-deposited catalyst layer. It was found that the morphology of ZnO could be changed through varying the ratio of Ag to Au in the alloy catalyst. The result demonstrates that new complex nanostructures can be produced controllably with appropriate alloy catalyst.
Authors : A. G. Ilie, L. Gavrila, C. Fleaca, E. Popovici, I. Morjan
Affiliations : National Institute for Laser, Plasma and Radiation Physics, Bucharest, Romania
Resume : In this work, we obtained ZnO-C nanoparticles using laser pyrolysis or solid state combustion methods, starting from zinc acetylacetonate monohydrate as Zn precursor, and ethylene as sensitizer in the gas phase method, or glycine as combustible in the solid method. Our aim is to compare these two types of methods, regarding the morphology and structure of the synthesized nanoparticles, using Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). The results of these studies will be useful in optimizing the synthesis methods mentioned above, in order to obtain specific characteristics of ZnO-C nanoparticles, and also, for choosing the appropriate method for the type of the desired outcome.
Authors : Tomoya Abiru, Fumiaki Mitsugi, Tomoaki Ikegami, Shin-ichi Aoqui, Kenji Ebihara
Affiliations : Graduate school of science and technology, Kumamoto Univ. Dep. of Computer & Information Sci., Sojo Univ. Environment and Energy Laboratory
Resume : In plasma-material processing, much focus has been placed on the influence of plasma derivative reactive species including ozone on soil materials. Becausechemical contamination in soilcausing ground water pollution has become serious by the overuse of pesticides and nitrogen fertilizers which are used to treat soil borne worms and enhance plants growth in agriculture, ozone treatment using plasma technology is one of the potential alternatives to those.We have proposed the use of ozone in oxygen plasma generated by surface barrier discharge for soil treatment. Since soil is composed from gas, solution, inorganic and organic substances, and microorganism, the effect of ozone treatment on soil should be investigated from chemical, physical, and biological points of view. We revealed several advantages of ozone treatment of soil in previous works. One is that ozone has strong potential to inactivate fungi and bacteria in soil, showing no high molecular DNA remained in soil after sufficient ozone treatment. Another is that the decomposition of soil organic substances leads the generation of inorganic nitrogen nutrients that are sucked up from roots of plants, accelerating growth of plants. In this work, the acidity of soil after ozone treatment is focused. Because soil acidity is defined as either active acidity showing acidity in soil solution or potential acidity showing acidity in soil solution and solid colloid, we evaluated active acidity and potential acidity with pH(H2O) and pH(KCl) methods, respectively. Ozone was generated from pure oxygen with the surface discharge device, injecting into the rotating quartz chamberbecause the use of the quartz chamber can avoid ozone consumption into unexpected organic matters. The concentration of ozone was about 80 g/m3 with the flow rate of the oxygen supply of 1.5 L/min. The exhaust gas was lead through an ozone monitor. Andosol (100 g) samples were treated for different treating times which range from 1 to 90 min. After treatment for 90 min., pH(H2O) and pH(KCl) decreased from 7.3 to 5.5 and 6.2 to 4.3, recovering 7.4 and 6.4 respectively after 14 days passed from the treatment. This suggested that the amount of hydrogen ions changed only in soil solution.Thus, it was found that hydrogen ions do not migrate from soil solution to soil colloid.
Authors : Mehmet Gursoy, Tuba Ucar, Handan Kamis, Mustafa Karaman
Affiliations : Selcuk University
Resume : The design and manufacture of surfaces that repel water have attracted remarkable attention. Hydrophobic surfaces have a broad spectrum of applications ranging from high technology textile to microelectronics. Fluorinated polymers are used to make a surface hydrophobic due to their low surface energy. A number of different methods are known for making fluorinated polymer surfaces; for instance, direct exposure to F2 gas, solgel processing, electrospinning, and chemical vapor deposition (CVD) of fluoromonomers. Among these methods, the nature of CVD tends to result in chemically homogenous films. In this study, a custom built cylindrical chamber having 16cm outer diameter and 10cm in height was used as the plasma polymerization reactor. Thin film of poly-hexafluoro butyl acrylate (PHFBA) was produced on a silicon wafer by plasma enhanced chemical vapor deposition (PECVD) method. The substrate stage is maintained at -10, 20, 40 and 60°C using a water circulated chiller. During all experiments, pressure in the reactor was maintained at 100 mtorr. FTIR analysis of the as-deposited films showed a high retention of perfluoro-alkyl functionality. Water contact angle measurements were carried out to determine the wettability of as-deposited PHFBA surfaces. The film thicknesses were measured in-situ during the experiments by laser interferometry method, making it possible to analyze the effect of substrate temperature on the deposition rates.
Authors : Shin-ichi Aoqui, Tamiko Ohshima, Hiroharu Kawasaki, Fumiaki Mitsugi
Affiliations : Dep. of Computer & Information Sci., Sojo Univ.; Dep. of Electrical & Electronics Eng., Sasebo National College of Tech.; Dep. of Electrical & Electronics Eng., Sasebo National College of Tech.; Faculty of Eng. Kumamoto Univ.
Resume : Gliding arc discharge is the unique middle electricity electric discharge which can work by atmospheric pressure. In our previous study, we showed that gliding arc discharge did not satisfy the requirements of normal arc discharge condition. In other words, the continuance requirements of discharge of gliding arc are not a large current with low voltage and electron is not supplied by thermionic emission condition. Depending on a shape of electrodes, gliding arc discharge may satisfy an arc condition, but many cases are not so. In addition, it has been understood that the discharge strongly depended on a velocity of supplied gas. Therefore we named it serpentine plasma as a name to distinguish from a normal arc discharge. The definition of discharge starting voltage in this work is the amplitude of applied voltage just before the start of discharge. Waveforms of applied voltage and discharge current were measured with a high-voltage probe (Tektronix, P6015A) and a current clamp (Tektronix, TCP2020), respectively. Both waveforms were captured with a digital oscilloscope (Lecroy WaveRunner 204Xi-A). Time-resolved digital photographs for plasmas were recorded by a high-speed digital camera (Phantom V1210) with 10,000-100,000 fps with external trigger signal from a pulsed signal generator (Hamamatsu, C10149). In addition, emission of spectroscopy observation of plasma was carried out. At the same time fine particles were generated by an operation gas kind was identified as electrode materials in gliding arc discharge by those observation. The fine particles based on the electrode metallic element were generated in particular easily when argon was used for operation gas. Several electrode materials were chosen in this study, and the sampling of the particle to a silicon substrate was carried out. The fine particles on a silicon substrate were analyzed by Electron Beam 3D surface roughness analyzer (Elionix, ERA-8900FE) with EDX. Emission spectroscopy observation and black body emission observation were carried out to confirm a reaction in the discharge space at the same time. Because gliding arc discharge device is extremely simple structure, and a power supply can apply it with a commercial power supply, low-cost fine particles preparation is enabled. In particular carbon-based nanoparticles may be provided easily when a carbon electrode is used.
Authors : C. Constantinescu, P. Delaporte, A.P. Alloncle
Affiliations : Aix-Marseille Universite / CNRS, Laboratoire LP3 (UMR 7341), F-13288 Marseille, France
Resume : Thin solid pixels made of Ag/PMMA stacks have been fabricated by laser-induced forward transfer (LIFT) to be tested as thin film microcapacitors in organic electronics applications. The transfer process is presented and the laser influence is particularly emphasized. The square-shaped printed capacitors are approximately 350 µm lateral size, while the thickness of the dielectric film was varied between 150 and 450 nm. The typical capacitance value was found in the pF range, and can be easily tuned by changing the properties of the multilayered structure (e.g. pixel size, thickness of the dielectric layer, etc). The use of optimal printing conditions led to the realization of microcapacitors with reproducible characteristics, but the structures were not stable over time. We discuss on the morphological and electrical properties of such structures, with respect to the rheological behavior of the polymer and its suitability for the LIFT process, when using a picosecond pulse duration UV laser (355 nm, 50 ps).
Authors : R. Cerrato, A. Casal, M. Mateo, G. Nicolas
Affiliations : Universidad de A Coru?a, Laboratorio de Aplicaciones Industriales del L?ser, Campus de Ferrol, Spain Tel.: 34 981337400x3274; fax: 34 981337410; firstname.lastname@example.org
Resume : Laser Induced Breakdown Spectroscopy (LIBS) technique has proven its ability to perform chemical maps on surfaces of numerous materials , i.e. spatial distribution of elements conforming the given specimen on the surface and beneath it. This analytical mode allowed, for example, to discriminate layers of different composition but with a certain thickness (coatings, layers with element enrichment?). The surface sensitivity of a technique is its capability to provide data from the surface of the sample. In the case of LIBS technique, it is mostly determined by the ablated-depth-per-pulse, which is in the range of tens of nm to several μm depending on the irradiation conditions. For this reason, due to the high crater depth generated during LIBS analyses, the applicability of this technique is quite limited in the characterization of very thin films. The purpose of this work has consisted of determining the ability of LIBS for the detection of oxide film formed on different metals. Several specimens (brass, steels and alloys) have been selected with an oxide film covering fully or partially the metal surface. The oxide film was formed by a natural way (age and ambient conditions) or by an artificial way (inside an oven) to produce different thicknesses of oxides in order to determine the minimal thickness that can be detected by standard LIBS conditions.  V. Pi?on, M.P. Mateo & G. Nicolas, Applied Spectroscopy Reviews 48 (2013) 357?383
Authors : C.T. Fleaca [1,2], F. Dumitrache [1,2], I. Morjan, C. Luculescu, A. M. Niculescu , A. Ilie , I. Stamatin , A. Iordache , E. Vasile , G. Prodan 
Affiliations :  National Institute for Lasers, Plasma and Radiation Physics (NILPRP), Lasers Department, 409 Atomistilor str., Magurele - Bucharest, Romania  Politehnica University of Bucharest, Applied. Sciences Faculty, Physics Department. 313 Splaiul Independentei, Bucharest, Romania University of Bucharest, Physics Faculty, 3Nano SAE Research Center, 405 Atomistilor str., Magurele-Bucharest , Romania  Politehnica University of Bucharest, Faculty of Materials Science and Engineering, 313 Splaiul Independentei, RO-060042, Bucharest, Romania  Ovidius University, Nanotechnologies and Alternative Energies Institute, 124 Mamaia Bvd., Constanta , Romania
Resume : We first synthesize the magnetic carbon encapsulated iron nanoparticles via IR laser-induced pyrolysis of Fe(CO)5 vapors in the presence of ethylene as sensitizer/carbon main precursor. The hydrophobic nanoparticles (with diameters under 20 nm) were then ultrasonically dispersed in water using sodiun salt of carboxymethylcellulose followed by anilinium chloride cold polymerization in acidic HCl solution on the their surfaces using ammonium persulfate. The resulted nanocomposite was magnetically separated from suspension, washed and dried. The TEM images of the composite show well-dispersed high contrast iron-based nanoparticles embedded in a disordered/amorphous matrix, while X-ray diffraction confirms the presence of metallic/carbidic phases, similar with those from raw Fe-C nanoparticles, which proves the resistance of these nanoparticles in the oxidant and acidic polymerization aqueous medium. FT-IR spectrum of nanocomposite also confirms the presence of bands characteristic to emeraldine salt. The composite have a ferromagnetic behavior with significant magnetization saturation (~ 6 emu/g). Moreover, cyclic voltammogram measurements show a higher electrochemical capacitance per mass unit than pure PANI synthesized in similar conditions. The feasability of our synthesis approach was proved also by the obtaining of a similar nanocomposite using alphanaphtylamine clorhydrate.
Authors : M. Socol1, N. Preda1, O. Rasoga1, C. Breazu1, F. Stanculescu2, G. Socol3, F. Gherendi3, V. Grumezescu3, N. Stefan3, M. Girtan4
Affiliations : 1 National Institute of Material Physics,105 bis Atomistilor Street, PO Box MG-7, 077125, Bucharest-Magurele, Romania 2 University of Bucharest, Faculty of Physics, 405 Atomistilor Street, PO Box MG-11, 077125, Bucharest-Magurele, Romania 3National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-36, 077125, Bucharest-Magurele, Romania 4Laboratoire de Photonique d'Angers, Universit? d?Angers, 2, Bd. Lavoisier, 49045, Angers, France
Resume : Organic heterostructures based on metal (Zn and Mg) phthalocyanes (p types semiconductors) and 5,10,15,20-tetra(4-pyrydil)21H,23H-porphyne (n type semiconductor) were prepare by Matrix-Assisted Pulsed Laser Evaporation (MAPLE) tehnique on ITO flexible substrates. Compositional, morphological and optical properties of the bilayer and bulk heterojunctions were investigated by UV-VIS, Photoluminescence (PL) and FTIR spectroscopy as well as Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The layers preserved the properties of the initial materials and exhibited a large absorption in the visible range of the solar spectrum. The morphology was typical to the MAPLE organic films with large grains. I-V characteristics of (Al/ZnPc(MgPc)/TPyP/ITO and Al/ZnPc(MgPc):TPyP /ITO) structures were recorded in dark and under the illumination with an solar simulator (AM1.5). Independent of the dye nature (Zn or Mg phthalocyane), we found out that the current value through the bulk heterojunctions was larger with at least one order of magnitude in comparison with the performances obtained for the bilayer heterojunctions.
Authors : R. Birjega1, A. Matei1, A. Vlad, B. Mitu1, M.Dumitru1,M.D.Ionita1, M. Dinescu1, R. Zavoianu2, O.D. Pavel2, M. C. Corobea3
Affiliations : 1)National Institute for Lasers, Plasma and Radiation Physics, Romania 2)Faculty of Chemistry, , University of Bucharest, Romania 3) National R.&S. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021, Bucharest, Romania
Resume : The aim of this work is producing thin films of layered double hydroxides (LDHs) and composite films of organo-modified LDHs by laser techniques for hydrophobic surfaces. LDH based on Mg-Al and Zn-Al with Me2+/Al3+ ratio of 2.5 were used as host materials while carboxylic acids and dodecyl sulfate acted as organic surfactants guest materials. Standard pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) have been employed for the growth of the composite layers. The organic anions were intercalated in co-precipitation step and subsequently the powders were used as materials for MAPLE or they were pressed and used as targets for PLD. The surface topography of the thin films was investigated by scanning electron microscopy and atomic force microscopy (AFM), the crystallographic structure of the powders and films was checked by X-ray diffraction, while spectral techniques (FT-IR, UV-vis) were used to evidence the interlayer composition, in particular of the organic component for both powders and thin films. The chemical composition was determined by energy dispersive X-ray analysis (EDX) and secondary ion mass spectrometry (SIMS). Contact angle measurements were performed in order to establish the wettability properties of the as-prepared thin films, for further applications as hydrophobic surfaces. The deposition conditions were found to strongly influence the film wettability.
Authors : A. Badoi1, F. Dumitrache1, 2, C. Fleaca1, 2, I. Morjan1, L. Gavrila1, M. Scarisoreanu1, N. Mihailescu1, C. Luculescu1, E Dutu1, A. Ilie1, G. Manda3, A. Cucu4, L. Vekas5, Ion Ciuca6
Affiliations : National Institute for Lasers, Plasma and Radiation Physics, Bucharest, Romania "Politehnica" University of Bucharest, Physics Department, Independentei 313, Bucharest, Romania  Victor Babes Natl Inst Pathol, Bucharest 050096, Romania Univ Bucharest, Fac Phys, Res Ctr 3Nano SAE, Bucharest 050663, Romania  Acad Romana, Timisoara Branch, RO-300223 Timisoara, Romania  POLITEHNICA Univ of Bucharest, Faculty of Materials Science and Engineering, Splaiul Independentei 313, RO-060042, Bucharest, Romania
Resume : In our days the functionalized magnetic nanoparticles play an important role in bio research because these classes of materials have different applications such as drug carriers with localized delivery, enhancing diagnosis methods or cellular labeling. Iron oxide based nanoparticles have been synthesized by CO2 laser pyrolysis using reactive mixtures containing iron pentacarbonyl vapors and oxygen diluted with argon. The experimental parameters were fixed in order to synthesize magnetic nanoparticles with a particle size distribution centered at few nm. In the present work, a new process for in-situ surface primary functionalization has been developed by supplementary introduction of different volatile compounds (acetone, methanol, water or acetic acid) as vapors in the reactive precursors mixture in order to generate functional groups at the surface of the freshly formed iron oxide nanoparticles. The as-synthesized iron oxide nanoparticles present improved dispersion capacity, non-cytotoxic characteristics and interesting magnetic properties. They have been characterized by XRD, TEM, EDX, FTIR and DLS techniques, and also their magnetic response at room temperature was measured. These raw particles were further biofunctionalized with chitosan/hyaluronan shells in PBS dispersions using the layer by layer method and then tested on human granulocytes. The cell internalization and low cytotoxicity (absence of ROS generation) was demonstrated for some of the biopolymer-coated nanoparticles.
Authors : ILHEM. R. KRIBA1*; K. BENOUMSAAD1; A. DJEBAILI2
Affiliations : 1 Plasma Laboratory - Faculty of Sciences Department of Physics- University of Batna- Algeria 2 Laboratory of chemistry and environmental chemistry L.C.C.E - University of Batna- Algeria,
Resume : The plasma spray coating technology is widely used in many sectors of industry to protect surfaces against thermal heat, wear, or corrosion. In plasma spray coating process, particles are fed into a high- velocity, high- temperature gas jet where they melt or partially melt while being propelled at high velocity onto the surface to be coated. Particles land on the solid surface where they spread, solidify and agglomerate to form a thin layer. The flattening characteristics of the droplets impinging on a substrate are important determinants in governing the eventual quality of the plasma spray coating. Because the mechanical performance of the coatings depends crucially on the particles flattening and intersplat bonding, such studies are very important to unravel the complex interaction between spray parameters and coating properties. Different codes have been developed in recent years to simulate the overall thermal spraying process, as well as the growth of the 3D coatings. The present investigation was carried out to have an approach to systematize the atmospheric plasma spraying process of two molten droplets in order to create a basis for numerically modelling the plasma dynamics, the coating formation mechanisms and to predict the particle thermo- kinetic state at impact. Key words: plasma spray, plasma dynamics, coating formation, thermo-kinetics
Authors : K. BENOUMSAAD1; ILHEM. R. KRIBA1*; A. DJEBAILI2
Affiliations : 1 Plasma Laboratory - Faculty of Sciences Department of Physics- University of Batna- Algeria 2 Laboratory of chemistry and environmental chemistry L.C.C.E - University of Batna- Algeria,
Resume : Plasma spray deposition is one of the most important technologies available for producing the high-performance surfaces required by modern industry. In this process, powder of the coating material is fed into high-temperature plasma, which melts and accelerates the powder; the molten particles subsequently hit and solidify on the surface to be coated. Most of the applications require coatings with a high density, which are well bonded to the substrate. To obtain good quality coating, the powder particle must be at least partially molten and hit the substrate with a high velocity. The flattening characteristics of the droplets impinging on a substrate are important determinants in governing the eventual quality of the plasma spray coating. Because the mechanical performance of the coatings depends crucially on the particles flattening and intersplat bonding, such studies are very important to unravel the complex interaction between spray parameters and coating properties different codes have been developed in recent years to simulate the overall thermal spraying process, as well as the growth of the 3D coatings, in which entrained particles are modeled by stochastic particle models, fully coupled to the plasma flow. Similarly to previous work, there are still a lot of assumptions involved in these codes, dealing with the shape of the droplets, the degree of splattering edge curl up, the porosity of the coating, and so on. The present investigation was carried out to have an approach to systematize the atmospheric plasma spraying process in order to create a basis for numerically modeling the plasma dynamics, the coating formation mechanisms and to predict the particle thermo- kinetic state at impact. Key words: plasma spray process, flattening, coating, solidification, numerical model
Authors : Z. SKANDERI1, A. DJEBAILI1*, J.P. CHOPART2
Affiliations : 1 Laboratory of chemistry and environmental chemistry L.C.C.E - University of Batna- Algeria 2 Laboratory of Mechanical Stress-Transfer Dynamics at Interfaces LACMDTI URCA,BP 1039, 51687 University of Reims Cedex2, France
Resume : The first originality of the experiments we carried out consists of the use of a laser beam as a double agent: simultaneously as activation agent inducing the isomerization reaction of the PA, and for the Raman diffusion. The laser beam power P(λ) is equivalent to the temperature T of isotherm i of isomerization reaction. The second originality consists of use of multichannel spectroscopy which enables the simultaneous observation of both reactants (PAcis) and product (PAtrans) in the same time, since PAcis absorption band and PAtrans absorption band are clearly shifted on a band of 512 diodes Then we have a double simultaneity (i) In one hand the heating and the diffusion of the laser beam, (ii) On the other hand the steady measurement of the concentrations. We elaborate a numerical model reproducing the Raman experiment within 5 % error. The rate constants, activation energy values, Arrhenius factors and linear regression coefficients are obtain with a small error. The kinetic results obtained, such as reaction orders values obtained, varying from 1/2 to 2/3, showed clearly that, the isomerization reaction of undoped P.A. remains a complex process. The reaction order of 2/3 seems to be the most appropriate value in this case, since it refers to a solid state reaction propagation, where the reaction rate is controlled by a three dimensional development of active centers, in agreement with Sestak and Berggren theory.
Authors : A. Matei1, C. Constantinescu1, V. Ion1, B. Mitu1, I. Ionita1,2, M. Dinescu1, A. Emandi3
Affiliations : 1INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest, Romania; 2UB - University of Bucharest, Faculty of Physiscs, 405 Atomistilor Str., Magurele RO-077125, Bucharest, Romania; 3UB - University of Bucharest, Faculty of Chemistry, 90-92 Şoseaua Panduri, Sector 5, RO-010184, Bucharest, Romania
Resume : We present results on a laboratory-synthesized ferrocene derivative, i.e. 4-amino(3-ferrocenyl methylidene)-salicylic acid. Thin films with controlled thickness were grown by matrix-assisted pulsed laser evaporation (MAPLE), on quartz and silicon substrates, with the aim of being further considered in nonlinear optical applications. Dimethyl sulfoxide was used as matrix, with 1% wt. concentration of the guest compound. The frozen target was irradiated with the fourth harmonic of a Nd:YAG laser (4ω / 266 nm, 7 ns pulse duration, 10 Hz repetition rate), at fluences ranging from 0.1 to 1 J/cm2. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to investigate the surface morphology of the films. Fourier transform infrared (FTIR) and Raman spectroscopy reveal similar structure of the grown films when compared to the starting material. The optical properties of the thin films were investigated by spectroscopic-ellipsometry (SE), and the refractive index dependence to the temperature was determined. The second harmonic generation (SHG) potential was investigated using a femtosecond Ti:sapphire laser (800 nm, 60-100 fs pulse duration, 80 MHz repetition rate), at 200 mW maximum output power, revealing that the SHG signal intensity is strongly influenced by the films thickness.
Authors : A.Visan1, A. Janković2, S. Eraković2, C. Ristoscu1, N. Mihailescu (Serban)1, L. Duta1, G.E.Stan3, A.C.Popa3,4, M.A. Husanu3, C.R. Luculescu1, V.V. Srdić5, Dj. Janaćković6, V.Miković-Stanković6, C. Bleotu7, M.C. Chifiriuc8, I.N. Mihailescu1
Affiliations : 1 National Institute for Lasers, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania 2Innovation Center, Faculty of Technology and Metallurgy, University of Belgrade, 11000 Belgrade, Serbia 3National Institute of Materials Physics, 077125 Magurele, Ilfov, Romania 4Army Centre for Medical Research, 020012 Bucharest, Romania 5Department of Materials Engineering, Faculty of Technology, University of Novi Sad, 21000 Novi Sad, Serbia 6Faculty of Technology and Metallurgy, University of Belgrade, 11000 Belgrade, Serbia 7Stefan S. Nicolau Institute of Virology, 030304 Bucharest, Romania 8Department of Microbiology, Faculty of Biology, University of Bucharest, 060101 Bucharest, Romania
Resume : Implant surface functionalization represents an advanced approach in implantology aiming to enhanced and prolonged biointegration. We report on thin film deposition of silver doped hydroxyapatite (Ag:HA) combined with the natural biopolymer organosolv lignin by matrix assisted pulsed laser evaporation (MAPLE). Aqueous water dispersions of Ag/HA/Lig composite and its counterpart without silver (HA/Lig) were frozen in liquid nitrogen to yield solid cryogenic target for KrF* excimer laser source. The expulsed material was assembled onto pure titanium foils and silicon wafers and subjected to SEM, EDS, ATR-FTIR, XRD and AFM analyses. The obtained coatings preserved their initial composition, as demonstrated by FTIR, XRD and EDS data. The high values of surface roughness of thus assembled Ag/HA/Lig thin film are in good compliance with the potential use in medicine and biology. Titanium surface modified in such a manner would help host cell proliferation and subsequently osteointegration of implant material.
Authors : A. Visan1, S. Erakovic2, A. Jankovic2, C. Ristoscu1, L. Duta1, N. Mihailescu (Serban)1, G.E. Stan3, M. Socol3, O. Iordache 4, I. Dumitrescu4, C.R. Luculescu1,I.N. Mihailescu1 Dj. Janackovic2, V. Miskovic-Stankovic2
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, Magurele, Romania 2Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia 3National Institute of Materials Physics, 105 bis Atomistilor Street, Magurele, Romania 4 Microbiology Immunology Department, Faculty of Biology, University of Bucharest, Romania
Resume : Hydroxyapatite (HA) is a widely used biomaterial for implant thin films, largely-recognized for its excellent capability to chemically bond to hard tissue inducing the osteogenesis without anti-immune response from human tissues. Nowadays, intense research efforts are focused on development of antimicrobial HA doped thin films. In particular, pure or doped HA with Silver (Ag:HA) is expected to inhibit the attachment of microbes and contamination of metallic implant surface. We report on the transfer by pulsed laser techniques of pure HA and Ag:HA on Ti and Ti modified with TiO2 nanotubes susbtrates. Obtained coatings preserved their initial composition, as demonstrated by physic-chemical analyses:FTIR, XRD and EDS data. The high values of surface roughness of thus assembled composite thin films are in good compliance with the potential use in medicine and biology. Titanium surface modified in such a manner would help host cell proliferation and subsequently osteointegration of implant material.The biological assays demonstrated the high antifungal efficiency of heat treated Ag:HA thin films deposited on Ti modified by TiO2 nanotubes substrates which completely exterminate Candida albicans and radically reduce the Aspergillus niger number of colonies. These results proved that the applied method allow for the fabrication of efficient shield barriers against adherence and contamination with pathogenic fungi.
Authors : A. Visan1, N. Stefan1, M. Miroiu1, C. Nita1, G. Dorcioman1, O. Rasoga2, I. Zgura2, C. Breazu2, A. Stanculescu2, R. Cristescu1, M.C. Chifiriuc3, M. Chiritoiu4, L. Sima4, F. Antohe5, L. Ivan5, I.N. Mihailescu1, G. Socol1
Affiliations : 1 National Institute for Lasers, Plasma and Radiation Physics, Magurele, Ilfov, Romania 2 National Institute of Materials Physics, Magurele, Ilfov, Romania 3 Faculty of Biology, University of Bucharest, Microbiology Immunology Department, Aleea Portocalelor 1-3, Sector 5, 77206 Bucharest, Romania 4 Institute of Biochemistry, Splaiul Independentei 296, Bucharest, Romania 5 Institute of Cellular Biology and Pathology Nicolae Simionescu, Bucharest,Romania
Resume : In this study, we investigated different synthesis methods for obtaining surfaces able to promote cellular adhesion, as well as reduce the risk of bacterial contamination, the main challenge being to obtain both effects on the same metallic implant surface. Lysozyme embedded into blends of polyethylene glycol (PEG) and polycaprolactone (PCL) were developed via Matrix Assisted Pulsed Laser Evaporation (MAPLE) and Dip Coating techniques for long term delivery applications. Different blend ratios were synthesized and evaluated to optimize protein release profile from fabricated coatings. The chemical composition (FTIR) and the main surface features which affect and guide cellular and bacterial adhesion like roughness (AFM), and wettability measurements were investigated. Antimicrobial properties of coatings against Escherichia coli and Staphylococcus aureus bacteria were also evaluated. In vitro culture tests on mesenchymal stem and endothelial cells grown on PCL-PEG-lysozyme coatings showed appropriate viability, good spreading and normal cell morphology. The release tests of lysozyme along with biological investigations suggest that our polymeric composite coatings with adjusted biodegradability may be efficient in preventing implant-related infections.
Authors : F. Zacharatos(1), N. Iliadis(2), J. Kanakis(2), P. Bakopoulos(2), H. Avramopoulos(2), I. Zergioti*(1)
Affiliations : 1. National Technical University of Athens, Physics Department, Heroon Polytehneiou 9, 15780, Zografou, Greece 2. National Technical University of Athens, School of Electrical & Computer Engineering, Heroon Polytechniou 9, 15780 Zografou, Greece *contact: email@example.com
Resume : Flexible electronics have emerged as a very promising alternative of CMOS compatible electronics for a plethora of applications. Laser microfabrication techniques, such as Laser ablation and Laser sintering are compatible with flexible substrates and have demonstrated impressive results in the field of flexible electronic devices and sensors. However, laser based manufacturing of RF passive components or devices is still at an early stage. In this work we report on the all-laser fabrication of Silver Co-planar Waveguides (CPWs) on Poly-EthyleneNapthalate (PEN) substrates. The CPWs have been fabricated to match 50 Ohm ports of an Anritsu Vector Network Analyzer operating from 300MHz - 40GHz, according to the design reported in previous work. The all laser fabrication process consisted of the patterning of a Silver Nano Particle layer spin-coated on a PEN substrate followed by the selective laser sintering of the structures with a ns pulsed Nd:YAG laser source operating at 532nm, according to the optimized parameters extracted from a previous study of the authors. The CPWs have been characterized electrically at the 0.3-40GHz regime and found to be excellent transmission lines with a 40GHz 3dB bandwidth, owing to the high electrical conductivity of Ag and the exquisite dielectric properties of PEN. This novel process is a milestone towards the RF technology transfer to flexible electronics with low cost and specs comparable or even superior to the CMOS compatible equivalents.
Authors : Valentina Grumezescu1,2*, Ecaterina Andronescu2, Dumitru Vezeteu2, Bogdan Drosu2, Adrian Vasile Surdu2, Otilia Ruxandra Vasile2, Bogdan Stefan Vasile2, Alexandru Mihai Grumezescu2, Gabriel Socol1, Florin Iordache3, Horia Maniu3
Affiliations : 1Lasers Department, National Institute for Lasers, Plasma & Radiation Physics, P.O. Box MG-36, Magurele, Bucharest, Romania 2Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 17 Polizu Street, 011061 Bucharest, Romania 3Institute of Cellular Biology and Pathology of Romanian Academy, Nicolae Simionescu, Department of Fetal and Adult Stem Cell Therapy, 8, B.P. Hasdeu, Bucharest 050568, Romania
Resume : Bone cancer represents one of the most frequent, severe and invalidating hard tissue cancer. After the surgical resection of the bone tumors, often a bone implant is fixed for increasing the health condition and life quality of the affected patients. However, this procedure may have severe side effects due to the increased rates of cancer relapse and associated severe infections, which occur with a higher rate in post chemo-therapy patients as a result of their induced immunosuppression. The aim of this research was to develop novel and sustainable solutions in order to prevent bone cancer relapse by optimizing the surface of endoprostheses. Coatings based on hydroxyapatite, polyethylene glycol and doxorubicin composites were deposited by Matrix Assisted Pulsed Laser Evaporation (MAPLE). Prepared surfaces were characterized by SEM, TEM, DTA-TG, SAED, XRD, AFM and IR Microscopy. Biological assays included qualitative (fluorescence microscopy) and quantitative (flow citometry and biochemical MTT assay) tests. In vitro assessments revealed a good anti-tumoral activity against tumoral cell lines. Furthermore, the microbiology assays revealed that synthesized surfaces inhibit microbial attachment of several Gram positive and Gram negative bacteria species.
Authors : F. Zacharatos(1), M. Makrygianni(1), R. Geremia(2), E. Biver(2), D. Karnakis(2), St. Leyder(3), D. Puerto(3), Ph. Delaporte(3), I. Zergioti*(1)
Affiliations : (1) National Technical University of Athens, Physics Department, Heroon Polytehneiou 9, 15780, Zografou, Greece (2) Oxford Lasers Ltd, Unit 8 Moorbrook Park, Oxfordshire, OX11 7HP, United Kingdom (3) Aix-Marseille University, CNRS, LP3 - UMR 7341, 13288 Marseille cedex 9, France *contact: firstname.lastname@example.org
Resume : To date, Laser Direct Write (LDW) techniques, such as Laser Induced Forward Transfer (LIFT), Selective Laser Ablation and Selective Laser Sintering (SLS) of metallic nanoparticle (NP) ink layers is receiving growing attention for the printing of uniform and well-defined conductive patterns. For flexible substrates in particular, SLS of such NP patterns has been widely applied, as a low temperature and high resolution process compatible with organic electronics. In this work, LDW of Ag NP inks has been carried out on PEN and PET flexible substrates to achieve low electrical resistivity electrodes. In more detail, high speed short pulsed (ps and ns) lasers with repetition rates up to 1MHz were used for the printing (LIFT) of the metal NP inks. As a result, uniform and continuous patterns with minimum feature size 50um have been achieved. Next, the printed patterns were laser sintered with ns pulses at 532nm over a wide laser fluence window, resulting in electrical resistivity of 10 uOhm.cm. Spatial beam shaping experiments were carried out to achieve a top-hat laser intensity profile and employ selective laser ablation of thin films (thickness on the order of 100nm), so as to produce silver micro-electrodes with resolution on the order of 10um and low line edge roughness. SLS was combined with laser ablation to constitute a fully autonomous micro-patterning technique with 10um resolution and geometrical characteristics tuned for interdigitated electrodes for sensor applications
Authors : Monica Scarisoreanu1, Claudiu Fleaca1, Ion Morjan1, Ana Maria Niculescu1, Catalin Luculescu1, Iuliana Morjan1, Elena Dutu1, Anca Badoi1, Alina Ilie1, Eugeniu Vasile2, Virginia Danciu3
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, POB MG-36, Bucharest 077125, Romania; 2 Metav, Research and Development, 31 C.A. Rosetti Str, 020011, Bucharest, Romania; 3,,Babes-Boyai University, Faculty of Chemistry and Chemical Engineering, Electrochemical Research Laboratory, 11 Arany Janos Str, Cluj- Napoca, 400028, Romania;
Resume : This work presents the preparation of TiO2/SnO2 composite nanoparticles using laser pyrolysis technique starting from sensitized mixtures of TiCl4 and Sn(CH3)4 precursors in the presence of oxygen. Nanocomposites with controlled Ti:Sn atomic ratios were produced at different flow rates of oxygen. Structural, morphological and optical properties of the obtained powders have been characterized by XRD, EDX, TEM and UV-Vis diffuse reflectance spectroscopy. The results indicate that the nanocomposite particles have a core-shell morphology contains a mixture of anatase and cassiterite phases with mean particle size at about 13-15 nm. Compared with pure components of TiO2 nanoparticles, these TiO2/SnO2 nanostructures demonstrated promising photocatalytic properties attributed to the combinational changes in Eg of the TiO2 phase and the increased specific surface area.
Authors : F. Bourquard ; C. Maddi ; A.-S. Loir ; C. Donnet ; F. Garrelie
Affiliations : Université de Lyon, F-69003, Lyon, France, Université de Saint-Étienne, Laboratoire Hubert Curien (UMR 5516 CNRS), 42000 Saint Étienne, France
Resume : This study is carried in the context of femtosecond Pulsed Laser Deposition of nitrogen doped diamond-like carbon films with plasma assistance, and is intending to establish a correlation between plasma diagnostic and CNx films properties. The ablation of graphite targets takes place in inert N2 atmosphere of DC N2 plasma. The goal of our work is to understand where and when the CN bonds are created in the expanding ablation plume, in order to explain the structure and composition of the deposited material. To do so, the ablation plume was studied through Optical Emission Spectroscopy using Intensified CCD gating to obtain nanosecond time resolution, which allows a timing of nitrogen and carbon bonding in the plume. Images of the plasma were also made using Intensified CCD gating and dichroic filters to identify the precise location of the various species in the expanding plume. Comparative study was carried in vacuum and argon atmosphere and DC plasma in order to get a reference of carbon plume composition and expansion behavior. The results are correlated to the properties of N-doped DLC thin films produced with the same experimental setup, explaining the contents and bonding properties of the material.
Authors : Dragos Radulescu1, Valentina Grumezescu2,3,*, Aurelian Iuscu4, Alina Maria Holban2,5, Alexandru Mihai Grumezescu2, Gabriel Socol3, Alexandra Elena Oprea2, Carmen Mariana Chifiriuc5,8, Roxana Trusca6, Miruna Silvia Stan7, Sabrina Constanda7, Anca Dinischiotu7, Radu Radulescu1
Affiliations : 1Bucharest University Hospital, Department of Orthopedics and Traumatology, 169 Splaiul Independentei, 050098 Bucharest, Romania 2Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 17 Polizu Street, 011061 Bucharest, Romania 3Lasers Department, National Institute for Lasers, Plasma & Radiation Physics, P.O. Box MG-36, Magurele, Bucharest, Romania 4 Center of Excellence, Research, Innovation and Business Development,31 Kepler, Bucharest, Romania 5Microbiology Immunology Department, Faculty of Biology, University of Bucharest, 13 Portocalilor Lane, Sector 5, 77206 Bucharest, Romania 6S.C. Metav-CD S.A., 31Rosetti Str., 020015 Bucharest, Romania 7Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independentei, 050095 Bucharest, Romania 8Research Institute of the University of Bucharest, Bd. M. Kogălniceanu 36-46, 050107, Bucharest, Romania
Resume : In this study we aim to obtain a tailored thin coating based on hydroxyapatite (HAP)/poly(lactic-co-glycolic acid) (PLGA) containing ceftriaxone or cefuroxine antibiotics (ATBs). Matrix Assisted Pulsed Laser Evaporation Tehnique (MAPLE) was used in order to deposit bioactive thin films. The prepared thin films were characterized by TEM, SEM, XRD, SAED, AFM and Infrared Microscopy. Biological characterization consisted in the in vitro evaluation of the thin film biocompatibility with respect to human osteoblast cells while their antimicrobial effect was analyzed by Staphylococcus aureus and Pseudomonas aeruginosa bacteria strains. Biocompatibility results demonstrated that HAP/PLGA/ATBs thin films present a good cytocompatibility related to the human osteoblasts, proving the ability of these non-toxic surfaces to sustain the cellular growth. Qualitative and quantitative analyses performed on S. aureus and P. aeruginosa strains showed that the obtained surfaces exhibited an inhibitory activity against microbial attachment and colonization. Furthermore, both microscopy and viable count analyses demonstrated ability of the thin film to inhibit biofilm formation of these bacteria species. All these data recommend this type of surface for prevention of microbial contaminations, biofilm development and for the stimulation of fixation at the bone-implant interface.
Authors : L. Duta1*, G.E. Stan2, M. Anastasescu3, H. Stroescu3, M. Gartner3, N. Mihailescu1, C. Luculescu1, S. Bakalova4, A. Szekeres4, I. N. Mihailescu1
Affiliations : 1National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, 077125 Magurele, Romania 2National Institute of Materials Physics, 105 bis Atomistilor Street, 077125 Magurele, Romania 3Institute of Physical Chemistry Ilie Murgulescu, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania 4Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784, Bulgaria
Resume : We report on multi-stage pulsed laser deposition of AlN on Si(100) wafers at different temperatures. The first stage of deposition was carried out at 800°C, the optimum temperature for AlN crystallization. The second stage is homoepitaxial deposition and was conducted at reduced temperatures (350°C, 450°C, RT) in low pressure nitrogen ambient at 0.1 Pa. The synthesized structures were analyzed by SEM/EDS, AFM, GIXRD, FTIR and spectroscopic elipsometry. In the SEM images, pyramidal shaped crystallites were visible. The cross-sectional SEM images revealed that the film thickness decreased when increasing the deposition temperature. For all samples, a quasi-stoichiometric Al/N atomic ratio was determined. When increasing the temperature, the surface of the samples presented a rather smooth aspect with RMS values below 0.7 nm. The two-stage deposited AlN samples exhibited diffraction patterns with peaks at (100), (002), (101), (102), (110), (103) and (112) of wurtzite AlN phase, pointing to the formation of small randomly oriented crystallites. The peaks were shifted to larger angles suggesting a smaller lattice distance in the crystallites. FTIR spectra showed a distinct broad peak at ~686 cm-1, originating from the E1(TO) phonon mode of AlN. Ellipsometric data analyses established band gap energy values in the range of (4.3‒4.8) eV for the formed AlN structures. From the comparison of these results with those of single-stage deposited AlN films, some conclusions were drawn.
Authors : E. Dutu1, F. Dumitrache1,2 , C. Fleaca1,2, C. Vlaic3, I. Morjan1, A. Bund3, A. Badoi1, A. M. Niculescu1 , I. P. Morjan1 , I. Sandu1 , E. Vasile4
Affiliations : 1 National Institute for Lasers, Plasma and Radiation Physics (NILPRP), Laser Photochemistry Laboratory, 409 Atomistilor Street, 077125, Magurele ? Bucharest, Romania 2 "Politehnica" University of Bucharest, Physics Department, Independentei 313, Bucharest, Romania 3 Department of Electrochemistry and Electroplating, Technische Universit?t Ilmenau, Gustav-Kirchhoff-Str. 6, 98693 Ilmenau, Germany 4 "Politehnica" University of Bucharest,, Faculty of Applied Chemistry and Material Science, Dept. of Oxide Materials and Nanomaterials, 1-7, Gh. Polizu Street, 011061 Bucharest, Romania
Resume : Continuous and pulsed Laser Pyrolsysis techniques have been used in order to synthesize homogeneous Fe/Co doped tin nanoparticles. Tetramethyltin, Iron pentacarbonyl and Cobalt tricarbonyl nitrosyl were the metal precursors. Three different ratios between iron /cobalt and tin precursor flows were tested: 1/40, 1/20 and 1/10. The ethylene presence in reactive mixture play only the role of transfer agent for laser energy. The optimal experimental conditions were determined by comparative parametric studies involving variations of laser power and precursor proportions in the reactive gas flow. The nanoparticles show spherical shapes with mean diameter between 80 and 35 nm, depending on metal doping level as TEM, SEM and XRD analyses revealed. The elemental compositions were evaluated with EDX technique. XRD and SAED analyses show only tin based crystals at low doping levels and traces of iron and/cobalt oxides for the highest doped samples. The metallic tin crystal has a high lithium insertion capacity and thus these nanoparticles reinforced by Fe and Co can have applications in Li- ion batteries. In order to validate their performance, our nanoparticles were tested using electrochemical measurements (cyclic voltammetry) using coin-type cells having metallic lithium cathodes.
Authors : V. ION (1), N.D. SCARISOREANU (1), A. ANDREI (1), A.I. BERCEA (1), F. CRACIUN (2), R. BIRJEGA (1), M. DINESCU (1)
Affiliations : 1) National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor St, RO-077125, Magurele, Romania; 2)CNR-ISC, Istituto Dei Sistemi Complessi, Via del Fosso del Cavaliere 100, I-00133 Rome, Italy
Resume : Lead-free (Ba1−xCax)(ZryTi1−y)O3 (BCZT) bulk materials are intesively studied in the last period for replacing piezoelectric and ferroelectric materials containing toxic elements in electronic applications. Different properties can be obtained ranging from normal ferroelectrics up to relaxor ferroelectrics by varying the the amount of A-site (Ca2+) and B-site (Ti4+) isovalent substitutions in BCTZ system. In this work, epitaxial strained thin films of BCTZ with composition around morphotropic phase boundary (MPB) were deposited using pulsed laser deposition method (PLD) on SrTiO3, LaAlO3 and GdScO3 substrates. The thin films structural features and induced microstrain due to the lattice misfit between the pseudocubic lattice parameter of the BCTZ (a=4.0176 Å) and the used substrates were studied by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM). A high refractive index and low extinction coefficient were obtained for all samples (n>2 and k<10-4 for near UV-VIS-near IR) by spectrometric ellipsometry. The dielectric properties (relative permittivity of about 2200 and tangent loss ~ 1-1.5% at frequency of 10 KHz) have been obtained by dielectric spectroscopy.. The local piezoelectric properties (d33~280 pm/V), polarization dynamics and switching characteristics of the samples were investigated by piezoresponse force microscopy technique (PFM).
Authors : L. Duta1*, G.E. Stan2, A.C Popescu1, A.C. Popa2,3,4, F. Miculescu5, I.N. Mihailescu1
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Magurele-Ilfov, Romania 2National Institute of Materials Physics, Magurele-Ilfov, Romania 3Army Centre for Medical Research, Bucharest, Romania 4Department of Cellular and Molecular Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania 5Politehnica University of Bucharest, Faculty of Materials Science and Engineering, Bucharest, Romania
Resume : We report on the synthesis by Pulsed Laser Deposition of bioactive glass (BG) thin films of SiO2Na2OK2OCaOMgOP2O5 compositional system onto ultra-high molecular weight polyethylene (UHMWPE) acetabular cups, and their characterization by immersion in simulated body fluids (SBF). After 42 days of immersion in SBF under homeostatic conditions, a partial dissolution of the BG film was observed, followed by the chemical growth of a carbonated hydroxyapatite layer. This behavior of the PLD glass coatings is the result of ion exchanges between BG and SBF solution, and is in accordance with the bioactivity mechanism proposed by Hench. Fourier Transform Infrared Spectroscopy indicated the strong depolymerization of the deposited BG coatings, favorable to a high bioreactivity and rapid osteointegration. The top-view Environmental Scanning Electron Microscopy showed significant morphological changes, the typical PLD film surface being converted after 42 days of immersion in SBF to a rough one consisting of acicular crystals. Energy Dispersive Spectroscopy analysis demonstrated the conservation of the targets stoichiometry after transfer. Moreover, the parent BG films showed an excellent purity, without any traces of contamination. We consider that the functionalization of UHMWPE acetabular cups with BG films by PLD opens good prospective for the fabrication of implants with improved osteoinductive characteristics.
Authors : G. Popescu-Pelin1,2, E. Axente1, F. Sima1, C. Nita1, A. Visan1, I. Zgura3, O.L. Rasoaga3, C.S. Breazu3, A. Stanculescu3, M. Chiritoiu4, L. Sima4, F. Antohe5, L. Ivan5, I.N. Mihailescu1, G. Socol1
Affiliations : 1 National Institute for Lasers, Plasma and Radiation Physics, Magurele, Ilfov, Romania 2 Faculty of Physics, University of Bucharest, Magurele, Ilfov, Romania 3 National Institute of Materials Physics, Magurele, Ilfov, Romania 4 Institute of Biochemistry, Splaiul Independentei 296, Bucharest, Romania 5 Institute of Cellular Biology and Pathology, B.P.HASDEU 8, Bucharest, Romania
Resume : Biodegradable polymers properties are preserved in vivo for a limited period of time and then slowly degrade into materials that are metabolized and excreted from the body. Lysozyme (Lys) embedded into simple and mixtures of poly(ε-caprolactone) (PCL) and poly(lactic acid-co-glycolic acid) (PLGA) in different ratios (1:3, 1:1, 3:1) have been deposited by matrix assisted pulsed laser evaporation (MAPLE) and dip-coating (DC) on Ti, glass and silicon substrates. We identify the optimum deposition conditions with respect to the structural, morphological, and wettability properties of films. In the case of MAPLE technique, PCL/PLGA/Lys composite films were deposited at 0.5 J/cm2 laser fluence, while for dip-coating the withdrawal speed was set at 100 mm/min. SEM investigations exhibited a dependence of surface morphology on the chemical composition, polymeric mixture ratio and deposition method. Fourier transform infrared (FTIR) spectrometry evidenced that the chemical composition of coatings deposited by both methods was conserved whereas the X-ray diffraction (XRD) studies revealed the presence of diffraction peaks of PCL only., Wettability tests performed on the polymeric coatings showed a hydrophilic behavior that depends on the polymeric mixture ratio and deposition method. In vitro tests performed with respect to osteoblasts and endothelial cells showed appropriate viability and cell morphologies.
Authors : I. Negut 1,2, C. Ristoscu 2, G. Soco l2, G. Stan 3, C. Chifiriuc 4, C. Hapenciuc 2, I. N. Mihailescu 2
Affiliations : 1 Faculty of Physics, University of Bucharest, Magurele, Ilfov, Romania, 077125 2 National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele - Ilfov, Romania 3 National Institute of Materials Physics, Bucharest - Magurele 077125, Romania 4 Faculty of Biology, University of Bucharest, Microbiology Immunology Department, Aleea Portocalilor 1-3, Sector 5, 77206 Bucharest, Romania
Resume : Diamond like carbon (DLC) was found to be a promising material for biomedical applications due to its biocompatibility, hemocompatibility, corrosion resistance, tribological and mechanical properties. The aim of this research was to produce adherent Ag/Si doped carbon layers deposited onto medical grade titanium substrates in order to provide to the medical implants good mechanical and antimicrobial properties and the ability to accelerate the osteointegration process. Our experiments involved the incorporation of Si into DLC for improving corrosion resistance in body fluid conditions and interfacial toughness of the medical implants. In order to obtain antimicrobial medical implants with enhanced antimicrobial properties we incorporated Ag in DLC nanopowders. Thin films of Ag/Si diamond-like carbon were grown onto medical grade titanium substrates by PLD, MAPLE and C-PLD methods using a KrF* excimer laser (λ = 248 nm, τFWHM = 25, ν = 10 Hz). The obtained thin films were physico ? chemically investigated. Transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, nanoindentation were employed to evaluate the morphological, structural, chemical and mechanical properties of the implant-type coatings. The biological response of the obtained thin films was evaluated preliminarily by in vitro investigations of the adherence, proliferation and cytotoxicity of the cells cultivated on the surface.
Authors : L. Duta1*, G.E. Stan2, N. Serban1, F.N. Oktar3-5, I. N. Mihailescu1
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, Magurele, Romania 2National Institute of Materials Physics, Magurele, Romania 3Department of Bioengineering, Faculty of Engineering, Marmara University, Istanbul, Turkey 4Department of Medical Imaging Techniques, School of Health Related Professions, Marmara University, Istanbul, Turkey 5Nanotechnology and Biomaterials Application & Research Centre, Marmara University, Istanbul, Turkey
Resume : We report on the feasibility of using hydroxyapatite [HA, Ca10(PO4)6(OH)2] from renewable biological sources for the synthesis of reliable implant-type coatings by pulsed laser deposition (PLD). Comparative studies on HA materials of synthetic or biological (ovine and bovine) origin, reinforced with Li2O or inert glass, were carried out. The biological HA (BHA) powders were calcinated according to a protocol which guarantees the full security against disease transmission and contamination. The role of reinforcement upon the structure and bonding strength of the PLD films was investigated. The morpho-structural properties of the films were evidenced by SEM-EDS, XRD, and FTIR spectroscopy, whilst their adherence to the Ti substrate was evaluated by pull-out tests. The films consisted of closely-packed spheroidal particulates with a mean diameter of ~2 µm. The EDS analysis revealed a slight carbonation of the BHA films, and the presence of Na, Mg, Cl, and Si traces. XRD and FTIR investigations evidenced the monophasic HA structure of the PLD films, with their crystallinity degree being influenced by biological origin and reinforcement type. The BHA films exhibited a higher value of adherence (~75MPa) as compared to the synthetic HA ones (~43MPa). Due to their improved performances and low cost fabrication from renewable resources, these new coating materials could represent a prospective competitor to synthetic HA for implantology applications.
Authors : V. Ion (1,2), N.D. Scarisoneanu (1), A. Andrei (1), R. Birjega (1), A.I. Bercea (1,2), M. Dinescu (1)
Affiliations : 1) National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor St, RO-077125, Magurele, Romania; 2) University of Bucharest, Faculty of Physics, 405 Atomistilor St, RO-077125, Magurele, Romania
Resume : The perovskitic materials with a small band gap value such as bismut ferrite (BiFeO3- BFO) have become very attractive for photovoltaic and photocatalytic applications. BFO exhibit both ferroelectric and ferromagnetic properties with a high remnant ferroelectric polarization (95 μC/cm2) and Curie temperature (Tc~1103 K). The band gap value of BiFeO3 (Eg~2.71 eV) corresponding to maximum absorptivity at visible wavelengths and, if doped with Yttrium or Lanthanum, the band gap value can be decreased even lower. In this work, BFO and La, Y-doped BFO thin films were deposited using pulsed laser deposition method (PLD) on various substrates. The purpose of this study was to obtain thin films of La, Y- doped BFO with small values of the band gap and to evaluate their photocatalytic applications. A parametric study on the influence of nature of substrate and substrate temperature during deposition on the properties of the La, Y- doped BFO thin layer was carried out. The band gap values (Eg) of the films were determined by spectroscopic ellipsometry (SE) and the structural features by x-ray diffraction and transmission electron microscopy. The local piezoelectric response, multiferoic and photocatalytic properties of the BFO and La, Y-doped BFO thin films have been studied using PFM, magnetoresitive and dielectric/ferroelectric spectroscopy.
Authors : Valentina Dinca1, Patricia Neacsu2, Anisoara Cimpean2, Laurentiu Rusen1, Simona Brajnicov1,C. Luculescu1, Maria Dinescu1
Affiliations : 1Lasers, National Institute for Lasers, Plasma and Radiation Physics, Bucharest, Romania 2 University of Bucharest - Department of Biochemistry and Molecular Biology, Bucharest, Romania
Resume : In this work, we explore the feasibility of using the Poly(ethylene glycol)-block-poly(ε−caprolactone) methyl ether copolymer as potential coatings for testing in vitro cell behavior. The films were deposited using Matrix Assisted Pulsed Laser Evaporation technique that allows good composition control and controlled thickness. The films were examined using Fourier transform infrared spectroscopy, contact angle measurements, atomic force microscopy, and cell culture-based studies. The Fourier transform infrared spectroscopy data demonstrated that the main functional groups in the MAPLE-deposited films remained intact. Characterization and evaluation of the coated substrates were carried out using different techniques. Scanning Electron Microscopy and Atomic Force Microscopy images showed the coatings to be continuous, with low surface roughness. The samples have been studied for in vitro biocompatibility by indirect contact tests on Vero cells in accordance with ISO 10993-5/2009. The results obtained in terms of cell morphology (phase contrast microscopy) and cytotoxicity (LDH and MTT assays) have proved biocompatibility. Furthermore, direct contact assays on MC3T3-E1 pre-osteoblasts demonstrated the capacity of all analyzed specimens to support cell adhesion, normal cellular morphology and growth. The financial support offered by CNCSIS through PCCA 239/2014 contract is acknowledged.
Authors : Valentina Dinca1, Valentina Mitran2, Nicu-Doinel Scarisoreanu1, D. Cojocaru3,Raluca Nicoleta Ion2, Patricia Neacsu2, Laurentiu Rusen1, Simona Brajnicov1, Valentin Ion1, C. Luculescu1,Anisoara Cimpean2, Maria Dinescu1
Affiliations : 1Lasers, National Institute for Lasers, Plasma and Radiation Physics, Bucharest, Romania 2 University of Bucharest - Department of Biochemistry and Molecular Biology, Bucharest, Romania 3 Polytechnic University of Bucharest Bucharest, Romania
Resume : In the last years, new composites based on inclusion of graphene into various compounds have attracted considerable interest within different applications, from sensors to biomedical systems. In this work, the composite films based on sericin and graphene were fabricated by Matrix Assisted Pulsed Laser Evaporation technique and used as coatings for pre-osteoblast cells assays. A Nd:YAG laser (λ = 266 nm, ν = 10 Hz), was used for the deposition experiments. The MAPLE target dispersions were prepared using sericin and graphene as host materials and DMSO-chloroform as solvent matrix. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), contact angle measurements, atomic force microscopy were used to characterize the structure and properties of the films. The materials deposited to the substrate surface resemble the initial starting materials used for the preparation of the MAPLE target dispersions. The cellular model used to evaluate the in vitro biocompatibility of sericin, graphene and sericin/graphene composite films was represented by MC3T3-E1 pre-osteoblasts. The release of lactate dehydrogenase (LDH) and LIVE/DEAD assay were assessed in order to evaluate cell cytotoxicity and cell survival of the pre-osteoblasts grown on the analyzed films. Our preliminary results indicate that all the samples exhibit no cytotoxic potential. The financial support offered by CNCSIS through PCCA 213/2014 contract is acknowledged.
Authors : N. D. Scarisoreanu (1), R. Birjega(1), V. Ion (1), A. Andrei (1), G. Stanciu (1), M. Dinescu (1)
Affiliations : 1. NILPRP, PO Box MG-16, RO-77125, Bucharest, Romania
Resume : We report on the electric and electro-optic properties of epitaxial strontium barium niobate (SrxBa1-xNb2O6- SBN) and Ca- doped SBN thin films deposited by pulsed laser deposition on MgO and Nb:STO substrates. The microstructure, morphology and stoichiometry were studied by XRD, AFM, SIMS, SEM and TEM. The XRD and HR-TEM analysis evidenced the formation of c-oriented SBN and Ca-doped SBN thin films. As a function of Ca doping level, the birefringence behavior and electro-optic coefficient (r33) of the thin films have been measured by reflection-type spectroscopic ellipsometry method, using coplanar AZO electrodes. The maximum measured change of the refractive index is Δn = -0.00646 for Ez=15 kV/cm, leading to a value for the electro-optic coefficients r33 of about 40.5 pm/V.
Authors : R.Pascu1, G. Epurescu1, S. Somacescu2, R.Birjega1, B. Mitu1, V. Ion1, M. Dinescu1
Affiliations : 1. National Institute for Laser, Plasma and Radiation, Magurele, Bucharest, Romania, 2. Ilie Murgulescu Institute of Physical Chemistry of the Romanian Academy, Bucharest, Romania
Resume : Dense Ni-8YSZ thin films have been grown by PLD to be used as anode in Solid Oxide Fuel Cells (SOFC). In order to obtain proper electrical properties in reducing or oxydizing atmosphere, one should control the amount of Ni incorporated in film, and to insure its uniform distribution inside the layer. For deposition, an ArF laser at 193 nm was used, which ablated a commercial YSZ target partially covered with Ni sectors to control the dopant concentration. An additional Oxygen RF discharge was assisting the deposition. Si and Si/Pt substrated were placed at 5cm in front of the target and were heated up to 600ºC. Morfological properties were studied by AFM and SEM, proving that no nichel agglomerations are present on the surface, while a roughnening tendency is observed upon increasing Ni content in the film. Structural properties and chemical composition were determined by XRD and XPS, respectively. They show the dispersion of Ni in the YSZ crystalline cubic matrix, and the presence of yttrium and zirconium in their full oxidation states. Dielectric Spectroscopy and Spectro-Ellipsometry techniques were used for determining the influence of Ni content on the electrical properties of Ni-YSZ thin films.
Authors : Daeho Kim*, Jaewon Lee, Seung Kwon Seol, Won Suk Chang
Affiliations : Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute
Resume : High temperature annealing of electronic devices printed with nano-materials such as metallic nanoparticles, graphene, carbon nano-tubes or their composites is an indispensable process to recover bulk properties of the materials. However, in flexible or stretchable devices, limited nano-materials could be compatible due to low operating temperature of the substrates. The Microwave is a versatile tool for selective heating of the printed nano-materials on thermally weak substrates because dissipating penetration depth of the microwave is around micro-meter for good conductors. The selectivity of the microwave heating suffers from conductive heat transfer which results small temperature gradient between the heated material and the substrate. Here we will demonstrate a highly intense and precisely controlled millisecond-speed microwave irradiation could perform selective high temperature annealing of the nano-materials on polymer substrates without thermal degradation by the heat transfer. And an in-situ Raman spectroscopy coupled with a microwave heating cavity was done for non-contact monitoring the real-time variations of the heated materials.
Authors : M. Makrygianni (1), S. Papazoglou (1), M. K. Filippidou (2), S. Chatzandroulis (2), I. Zergioti (1)*
Affiliations : 1. National Technical University of Athens, Physics Department, Zografou Campus Greece, 15780 *corresponding author: email@example.com 2. Inst. of Nanoscience and Nanotechnology, NCSR Demokritos, Agia Paraskevi, Greece, 153 10
Resume : Laser Induced Forward Transfer (LIFT) of metallic nanoparticles (NPs) ink is receiving growing interest as it offers an alternative non-lithographic technique for printing well-defined conductive lines. Laser printing of such NP patterns has been widely applied, as a low temperature and high resolution process compatible with organic electronics. In this work, the dynamics of the LIFT process was studied by using an experimental setup which is comprised of an Nd:YAG laser source (λ=266 nm, τ = 10 ns) and an image projection laser printing system. In this regard, two kinds of donor substrates were tested in terms of their efficiency for LIFT: by spin coating the copper NPs ink on i) quartz and ii) Ti coated quartz substrates. It was found that titanium DRL assisted LIFT resulted in smooth and low velocity (20-50 m/s) jetting behavior, for a wide laser process window (180-300 mJ/cm2), indicating therefore, a great potential for a high quality direct printing process. Next, printing of Silver and Copper lines was achieved on flexible substrates (PI). Continuous lines with 30-40% overlap of the printed ink droplets resulted in the best results in terms of morphology. The structural properties of the all-laser fabricated electrodes were characterized by optical, SEM and AFM microscopy and electrical measurements yielded in low resistivity electrodes (in the case of the printed Ag NPs electrodes). Finally, all laser printed chemical sensors were realized by printing reduced graphene oxide droplets on top of the pre-deposited electrodes on PI substrates. The sensors response upon humidity or ethanol flow was evaluated by measuring the electrical resistance variations of the sensing layer as a function of the surrounding environment.
Authors : Alexandra Elena Oprea1, Valentina Grumezescu1,2, Aurelian Iuscu3, Alina Maria Holban1,4, Otilia Vasile1, Laurentiu Mogoanta5, George Dan Mogosanu6, Alexandru Mihai Grumezescu1, Gabriel Socol2, Carmen Mariana Chifiriuc4, Roxana Trusca7, Miruna Silvia Stan8, Sabrina Constanda8, Anca Dinischiotu8
Affiliations : 1Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 17 Polizu Street, 011061 Bucharest, Romania 2Lasers Department, National Institute for Lasers, Plasma & Radiation Physics, P.O. Box MG-36, Magurele, Bucharest, Romania 3 Center of Excellence, Research, Innovation and Business Development,31 Kepler, Bucharest, Romania 4Microbiology Immunology Department, Faculty of Biology, University of Bucharest, 13 Portocalilor Lane, Sector 5, 77206 Bucharest, Romania 5 Research Center for Microscopic Morphology and Immunology, University of Medicine and Pharmacy of Craiova, 2 Petru Rareş Street, 200349 Craiova, Romania 6Department of Pharmacognosy & Phytotherapy, Faculty of Pharmacy, University of Medicine and Pharmacy of Craiova, 2 Petru Rareş Street, 200349 Craiova, Romania 7S.C. Metav-CD S.A., 31Rosetti Str., 020015 Bucharest, Romania 8 Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independentei, 050095 Bucharest, Romania
Resume : The aim of this study was to develop nanostructured bioactive surfaces based on ZnO and usnic acid (UA) with reduced side effects but with a great antimicrobial activity by limiting the attachment and biofilm formation of the pathogens. ZnO nanoparticles were prepared by sol-gel method and were functionalized with C18 and usnic acid. The functionalized nanoparticles were characterized by TEM, SEM, SAED, XRD, DTA-TG and FT-IR. Thin films were fabricated by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique and further characterized by TEM, SEM, AFM and IRM. In vitro biological response of the prepared coatings with respect to human skin fibroblasts was investigated by observation of cell morphology and attachment as well as nitric oxide (NO) release as an indicator of inflammation and cell death. Our qualitative and quantitative microbiological results have demonstrated that the bioactive coatings significantly inhibited the colonization of Salmonella enterica. Furthermore, both viable count assay and microscopy analysis revealed that biofilm formation is significantly impaired when bacteria grow on the prepared thin films. Our results recommend this material as an efficient approach in developing anti-infective coatings with good biocompatibility in order to be used in various industrial, medical and food processing environments.
Authors : Satoshi Kurumi, Yusuke Takahara, Kenichi Matsuda, Kaoru Suzuki
Affiliations : Nihon University
Resume : In this study, we had fabricated the Schottoky-device using Ga-doped diamond-like amorphous carbon (DLC) films on a Si substrate to apply a nano-micro varistors. i-DLC films, whose thickness was 500 nm, were deposited by ionization vapor deposition, and Ga ion beam as acceptor source was irradiated to this i-DLC films, which irradiated area was wide: 50 um, length: 450 um. In order to develop the DLC Shottoky device, we had deposited Al electrodes, which performed ohimc contact with the Ga implanted DLC film, by vacuumed deposition method. Additionally, Pt electrodes as Shottoky-contact material were grown by focused ion beam nano/micro deposition techniques. The Raman spectra of Ga ion implanted DLC films and non-implanted DLC films showed typical DLC characteristics by Raman spectroscopic analysis. We examined the relationship between electrical resistivity and Ga dose by the two probe method. The electrical resistivity of DLC films decreased with an increase in the Ga ion dose. Also, the current passing through a nanosized area of the DLC films implanted with Ga ions increased with increasing voltage. This Schottoky-device shows diode characteristic, but this cannot expect as a rectifier diode because keeping good characteristic value n is very high. On the other hand, varistor voltage of this device is 14.2 V. It is the same value with current chip varistor device.
Authors : A. Casal, R. Cerrato, M. Mateo, G. Nicolas
Affiliations : Universidad de A Coruña, Laboratorio de Aplicaciones Industriales del Láser, Campus de Ferrol, Spain Tel.: +34 981337400x3274; fax: +34 981337410; firstname.lastname@example.org
Resume : Laser Induced Breakdown Spectroscopy (LIBS) is in general considered as a non-quantitative method limiting its field of application to a qualitative approach in many cases. The explanation of this limiting factor is often simple and concerns the non-constant material removal which induces non repetitive LIBS data. This occurs when an analysis is performed on the same point or at different locations on a sample. This study shows how the LIBS intensity is linked to the evolution of the crater generated on different solid materials and consequently to the ablated volume. An in situ visual inspection of the laser spot generated at each pulse was achieved with an automatized optical microscope coupled to the laser ablation setup. From the images of the sample surface taken during the irradiation process, a reconstruction of the crater was made in 3D and the subsequent material ablated profile was generated. From the comparison between these spatial profiles and LIBS intensities, it can be easily understood that the non-repetitive LIBS data are induced by a non-constant ablation due to an inhomogeneous laser profile.
Authors : Rebecca B. Ettlinger(1), Andrea Cazzaniga(1), Andrea Crovetto(2), Stela Canulescu(1), and Jørgen Schou(1)
Affiliations : (1)DTU Fotonik, Technical University of Denmark, DK-4000 Roskilde, Denmark (2) DTU Nanotech, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
Resume : Pulsed laser deposition with different laser wavelengths may give rise to differences in the deposited films. The exact laser-material interactions are not easily predicted in detail and we have therefore made an experimental study in the UV-regime. We have used a 248 nm excimer laser and a 355 nm frequency doubled Nd:YAG laser on the materials ZnS and CTS (Cu2SnS3). In particular, as droplets on the film surface are a problem in deposition of CTS at 355 nm, we want to confirm whether using a shorter wavelength will result in fewer droplets. We also compare deposition rate, composition and crystal structure at different substrate temperatures. The deposition rate of ZnS may be higher with the 248 nm laser than the 355 nm laser, as the 248-nm photons are above the energy band gap. For CTS, the deposition rate may not be impacted significantly by the laser type. For both materials, the higher energy of the laser photons at 248 nm may cause higher-energy structures to form at lower substrate temperatures. There may also be important differences in the amount of volatile components (S, SnS) lost during the deposition process. Characterization will be done using Dektak profilometry, scanning electron microscopy, X-Ray diffraction, and energy dispersive X-ray spectroscopy.
Authors : Qin Wei Wei，Li Tao, Hu Xue Feng, Huang Shengming, and Wei Zhang
Affiliations : State Key Laboratory of Material-oriented Chemical Engineering and School of Chemical Engineering, Nanjing Tech University, Nanjing, Jiangsu 210009, PR China
Resume : The fundamental principle of ZnO nanogenarator is to utilize the environmental mechanical energy, which is available from irregular vibrations and human activity with a wide spectrum of frequencies and time-dependent amplitudes. The prototyping of a recent nanogenarator by means of ZnO piezoelectric nanowire (NW) arrays have demonstrated to able to drive micro-sensor and in micro-power range. However so far the power output from NW nanogenarator is still below micro watt, which is far away from milli-power output source requested by most applications of individual sensor. The mechanism understanding of piezo-electric conversional in ZnO material and device is crucial to further boost power output. In this paper, ZnO films grown by pulsed-laser deposited (PLD) in the oxygen pressure range of 5-40mTorr are investigated. The grown films are structurally characterized by XRD, SEM and AFM. The piezoelectric properties of these films are characterized by Piezoelectric Force Microscopy (PFM). The free-carrier density is characterized by CV and Hall-effect station. It is found that the piezoelectric properties of the films are strongly dependent on free-carrier density. The observed corresponds of piezoelectric (PE) property to grain size is also theoretically explained by the combination mechanism of free-carrier and static-charge.
Authors : Qin Wei Wei, Li Tao, Hu Xue Feng, Huang Shengming, and Wei Zhang
Affiliations : State Key Laboratory of Material-oriented Chemical Engineering and School of Chemical Engineering, Nanjing Tech University, Nanjing, Jiangsu 210009, PR China
Resume : Engineering, Nanjing Tech University, Nanjing, Jiangsu 210009, PR China Recent discovery in ZnO nanogenarator has spurred tremendous interest in micro sensor power application. The fundamental principle of ZnO nanogenarator is to utilize the environmental mechanical energy, which is available everywhere from irregular vibrations, light airflow, noise and human activity with a wide spectrum of frequencies and time-dependent amplitudes. The first prototyping of a nanogenarator by means of ZnO piezoelectric nanowire (NW) arrays, piezoelectric nanostructured materials have demonstrated to able to drive micro-sensor and sensor network nods in micro-power range. However so far the power output from NW nanogenarator is still in the power range micro watt, which is still far way from milli-power output source requested by most applications of individual sensor and sensor network system. The lacking of high power output in current ZnO NW generator is partially attribute to non-well c-axis oriented crystalline of ZnO NW material and low yield in NW device, both are synthesized by chemical method. In this paper, the piezoelectric properties of ZnO film grown by pulsed-laser deposited (PLD) in the temperatures range of 400 to 600 degree are investigated. Structurally, special emphasis is placed on XRD grain size characterizations of the grown films. Additional characterizations using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) will be detailed at a later date. The piezoelectric properties of these films are characterized by Piezoelectric Force Microscopy (PFM). It is found that the piezoelectric properties of the films are strongly dependent on grain size of the films. The observed corresponds of piezoelectric (PE) property to grain size is also theoretically explained.
Authors : Arun Kumar, I. Manna, S. K. Roy and J. Dutta Majumdar
Affiliations : Indian Institute of Technology Kharagpur
Resume : In the present study, mechanical and electrochemical properties of plasma nitrided and nitrogen-ion implanted Ti-6Al-4V coating deposited on AISI 316L stainless steel by DC magnetron sputtering technique have been undertaken. Microstructure of sputtered surface consists of nano-grained -Ti in the form of particulates and clusters. Nitriding and nitrogen ion implantation lead to formation of titanium nitrides (TiN, Ti2N and TiN0.3) on the surface. Improved mechanical (nanohardness and youngs modulus) and electro-chemical (corrosion) properties were observed on the coated surface.
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Fundamentals of laser-matter interaction I : J. Bonse
Authors : Jan Siegel
Affiliations : Laser Processing Group, Instituto de Optica, Spanish National Research Council (CSIC), Serrano 121, 28006 Madrid, Spain
Resume : The talk will provide an overview of the use of fs time-resolved microscopy for studying the interaction of ultrashort laser pulses with dielectrics. This technique constitutes a powerful pump-probe tool for imaging ultrafast ablation and non-linear propagation, providing a means for optimization of fs-laser processing applications related to the fabrication of high precision micro-/nanostructures and integrated photonics devices. Applied to surface processing, fs-microscopy has the capability of imaging and quantifying laser-induced free-electron plasmas and their temporal evolution. Establishing a relation between local plasma densities and material modifications becomes especially important when searching for optimum temporal pulse shapes for tailored processing. In some dielectrics a transient ring pattern can be observed within the ablating region that changes for increasing pump-probe delays. These transient Newton rings point towards an ablation mechanism based on the expansion of a transparent thin shell, similar to that found in metals and semiconductors. When applied to bulk processing inside dielectrics, fs-microscopy unveils numerous complex interaction mechanisms, including self-focusing, beam filamentation and pre-focal energy depletion, strongly deteriorating the spatial distribution of the deposited laser energy. We show how these undesirable effects can be minimized by adjusting the processing parameters, enabling the fabrication of optimized structures.
Authors : S.A. Irimiciuc1,2, S. Gurlui1, P. Nica3, M. Agop3, M. Osiac4, C. Focsa2
Affiliations : 1) Faculty of Physics, Alexandru Ioan Cuza University, 700506 Iasi, Romania 2) Laboratoire de Physique des Lasers, Atomes et Molécules, Université Lille 1, 59655 Villeneuve dAscq, France 3) Department of Physics, Gh. Asachi Technical University, 700050 Iasi, Romania 4) Faculty of Physics, University of Craiova, 200585 Craiova, Romania
Resume : Plasma plumes generated by femtosecond laser ablation of several metals (W, In, Te, Mn, Ni, Cu, Al) were investigated through Langmuir probe measurements. The aim of these experiments has been to establish a link between the plasma characteristics (temperatures, electron density, average charge state) and the physical properties of the targets (electrical and thermal conductivities, melting, boiling points etc.). The experiments were performed at various background pressures (10-2 -10-5 Torr), target biases and probe-target axial distances. The time-dependence of the probe current is studied assuming a shifted Maxwellian velocity distribution. By applying various probe biasing voltages and current time-integration, the probe volt-ampere characteristics were obtained. Two types of particles (hot and cold) are evidenced as having different temperatures and expansion velocities. An additional positive target biasing gives a residual ion current as consequence of center-of-mass velocity changing, and the probe characteristic is shifted with a constant value. At higher pressure (~10-2 Torr), an interesting behavior was observed in the electronic branch of the volt-ampere probe characteristics: periodic drops of the current for specific values of the probe bias. Some hypothesis on the origin of this peculiar behavior will be presented, along with a tentative correlation with the physical properties of the various metals investigated.
Authors : Gregoire Chabrol, Adline Ciceron, Patrice Twardowski, Pierre Pfeiffer, Manuel Flury, Frederic Mermet, Sylvain Lecler
Affiliations : IPP, ICube, ECAM Strasbourg-Europe; IPP, ICube, Télécom Physique Strasbourg; IPP, ICube, INSA Strasbourg; IREPA LASER
Resume : Thanks to recent advances in ultra-short pulsed laser manufacturing, reliable and high power Femto second lasers can now be used to process materials with a high degree of accuracy and resolution. Additionally, the non-linear absorption process taking place at the laser/material interface has widened the range of materials that can be processed. Diffractive Optical Element (DOE) manufacturing is a time consuming process involving many steps: coating, mask alignment and etching. Direct engraving of the DOE with a laser beam could be a very efficient means of rapid prototype manufacturing. Successful machining of a DOE in BK7 was obtained using an Amplitude Tangerine Femtosecond laser combined with a high-performance linear motor stage. The surface functionalisation was performed with a beam at a wavelength of 343 nm, a pulse width of 350 fs and a pulse energy of 20 ?J. By focussing the laser beam with a microscope objective, a binary phase grating with a period of 20 ?m, a groove depth and width of 1 ?m and 8 ?m respectively, was machined. The DOE profile was characterised by white light scanning interferometry and the diffractive efficiency measurements were corroborated by simulations performed by a Rigorous Electromagnetic Fourier Modal Method, taking into account the measurement profile. These encouraging results prove that high-speed femto second laser manufacturing of DOE in bulk glasses can be achieved, opening the way to rapid prototyping of multi-layered-DOEs.
Authors : Inam Mirza (1), Martin Hamar (2), Vaclav Michalek (2), Ondrej Haderka (2), Nadezhda M. Bulgakova (1,3), Danijela Rostohar (1),Tomas Mocek (1)
Affiliations : 1-HiLASE Centre, Institute of Physics ASCR, v.v.i, Dolní Břeany Czech Republic; 2-Institute of Physics AC SR, Joint Laboratory of Optics of PU and Inst. Phys. AS CR, Olomouc, Czech Republic; 3-Institute of Thermophysics SB RAS, Novosibirsk, Russia
Resume : In recent years, there has been a growing interest in ultrafast (femtosecond) laser processing of transparent materials and thin glasses for clean, efficient and high quality cutting and drilling. In this work, we study a concept that ultrashort laser pulses ensure laser ablation with lower heating of glass matrix at reduced thermal stresses as compared to longer pulses. Furthermore, avalanche ionization can be considerably suppressed by limiting number of free electron collisions via shortening the pulse duration and/or reducing laser fluence per pulse. The results will be presented on comparison of ultrafast laser ablation of fused silica and Willow glasses, which have different thermophysical and optical properties. Single- and multi-shot laser ablation was performed by Ti:sapphire laser operating at wavelength of 800 nm with pulse duration of 130 fs. A range of techniques such as optical profilometry, scanning electron microscopy, and space-and-time resolved spectroscopy were used to study crater profiles and quality as well as optical emission from laser ablated material and air plasma excited in front of the irradiation spot. The effect of varying fluence for femtosecond laser pulses was also studied. Damage thresholds for samples under study are compared. The excitation levels and glass temperature were evaluated based on the rate and energy equations.
Authors : K. V. Khishchenko
Affiliations : Joint Institute for High Temperatures RAS, Moscow, Russia
Resume : Modeling of thermodynamic properties and phase transitions of materials is required at numerical simulation of processes of intense pulsed influences on condensed media. In the present work, an equation-of-state model for silica is proposed with taking into account the polymorphic transformations, melting and evaporation effects. As distinct from the previously obtained multiphase equations of state, new expressions for the thermodynamic potentials are formulated. Those provide for a more correct thermal contribution of heavy particles in the liquid phase under rarefaction. A critical analysis of calculated results is made in comparison with available experimental data for silica over a wide range of densities and temperatures.
Authors : P. A. Atanasov1*, N. E. Stankova1, N. N. Nedyalkov1, N. Fukata2, S. Amoruso3, X. Wang3
Affiliations : 1Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Blvd., Sofia 1784, Bulgaria. 2International Center for Materials for NanoArchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1Namiki, Tsikuba 305-0044, Japan 3Coherentia CNR-INFM and Dipartimento di Scienze Fisiche, Università degli Studi di Napoli Federico II, Complesso Universitarion di Monte S.Angelo, Via Cintia, I-80126 Napoli, Italy
Resume : Medical grade polydimethylsiloxane (PDMS) elastomer is a widely used biomaterial in medicine and for production of high-tech devises MEMS and NEMS. Up to now, samples of PDMS-elastomer are processed by UV or VIS fs- and ns-laser pulses. The tracks produced are successfully metalized by Pt or Ni via electroless plating. The metallization process is found to be not sensitive with respect to the time interval after the laser treatment. In this work we present much wide study of the PDMS-elastomer processed by IR, VIS and UV fs-laser pulses. Different processing parameters as laser wavelength, pulse duration, fluence, scanning speed and overlapping of the subsequent pulses are varied in order to activate and change of the surface morphology. High definition tracks are produced. Analyses by AFM, SEM and Raman scattering analyses are accomplished in order to get information about the alteration of the chemical composition and structural morphology of the ablated traces. All properties will be compared with those of the native material. Our results will confirm the promising expectation with respect to use such a laser-based method for micro- or nano-fabrication of hi-tech PDMS devices.
Authors : Juergen Reif, Olga Varlamova, Markus Ratzke, Sebastian Uhlig*
Affiliations : Brandenburgische Technische Universitaet BTU Cottbus-Senftenberg, *present address: Fraunhofer IPMS, Dresden
Resume : Several types of regular nanostructures were produced at the surface of an old, filled hard disk by irradiation with a femtosecond white light continuum. The 40-Gb disk consists of a glass substrate, covered by a 100 nm thick magnetic film and a 5 nm protecting cover layer. In most of the irradiated area, the film structure is replaced by a regular array of bubbles with average diameters of 250 nm. From the substantial extension of these spheres above the original virgin film surface we conclude that they are spheres of rearranged, aggregated film material. This assumption is further supported by the fact that, at the spot edge, regions of completely removed film are adjacent to even larger spheres with diameters up to 1 µm. Even further out at the spot edge, arrays of long (1.5 7 µm) parallel lines are found in regions where the protecting cover layer is removed, with a width of about 400 nm and a separation of about 500 nm. These lines are, again, higher than the surrounding surface by 20 nm, and are sub-structured in 200-nm long segments of 10-nm height. It is not yet clear whether these structures are remnants of the magnetic bit structures of the hard disk.
Authors : T. J.-Y. Derrien (1), N. M. Bulgakova (1,3), L. Gemini (1,2), J. Limpouch (2), D. Rostohar (1), T. Mocek (1)
Affiliations : (1) HiLASE Centre, Institute of Physics, Academy of Science of the Czech Republic, Za Radnicí 828 828/5, 25241 Dolní Břeany, Czech Republic; (2) Czech Technical University in Prague, FNSPE, Brehova 7, 115 19 Prague, Czech Republic; (3) Institute of Thermophysics, SB RAS, Novosibirsk 630090, Russia
Resume : Multi-pulse femtosecond-laser irradiation of semiconductors in air leads to the formation of sub-wavelength periodic surface structures. The origin of laser-induced periodic surface structures (LIPSS) remains an open problem and still requires advanced theoretical studies. Recently, the role of Surface Electromagnetic Waves (SEW) was demonstrated theoretically and experimentally in several studies on temporal evolution of material surfaces after single-pulse excitation and under double-pulse irradiation with different separation time. However, theoretical predictions of LIPSS period remains imprecise. In this work, using 40 fs, 800-nm pulse irradiations, periodic structures perpendicular to the laser polarization were obtained on bulk silicon and silicon carbide films deposited on a Si substrates. Several SEW models were compared with the experimental measurements as a function of laser fluence. As a result, the structures on the bulk Si with near-wavelength period are quantitatively explained by the Sipe-Drude model, while on the SiC film the LIPSS with period of 100-150 nm are well described by laser coupling of Surface Plasmon Polaritons (SPP-Drude model) excited at the SiC-Si interface.
Laser-induced micro- and nanostructures II : O. Varlamova
Authors : E. L. Gurevich
Affiliations : Ruhr-University of Bochum, Germany
Resume : Laser-induced periodic surface structures (LIPSS) can be found on the surface of metals, dielectrics and semiconductor materials processed with single and multiple femtosecond laser pulses. The existing models of the femtosecond LIPSS formation try to describe periodic modulation of the electron and ion temperatures. However the mechanism how the temperature profile can result in a periodically-modulated surface profile in such a short time (less than 1 nanosecond) is still not clear. Estimations made on the basis of different hydrodynamic instabilities allow to sort out some mechanisms, which can bridge the gap between the temperature and the surface profile formation.
Authors : Álvaro Rodríguez-Rodríguez1, Esther Rebollar2, Michelina Soccio3, J.V. Garcia-Ramos1, T.A. Ezquerra1, M. Castillejo2, M.C. García-Gutiérrez1
Affiliations : 1Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, Madrid 28006, Spain; 2Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 119, Madrid 28006, Spain; 3Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, DICAM-Università di Bologna, Via Terracini 28, 40131 Bologna, Italy
Resume : Sub-microstructured polymer films on solid substrates are used in many technological applications as optical elements, photonic crystals, high-density magnetic data storage devices and biosensors. In particular, semiconducting polymers like poly(3-hexyl thiophene) (P3HT) have been widely studied as active layers in organic thin film transistors and organic photovoltaic solar cells. Here we report on the formation of laser induced periodic surface structures (LIPSS) in P3HT thin films upon irradiation with the linearly polarized second and fourth harmonics of a Nd:YAG laser (532 and 266 nm, 8 ns pulses). By optimizing irradiation parameters (number of pulses and laser fluence) polymer gratings with different levels of order can be obtained. In particular, the high optical absorption of P3HT at 532 nm enables the formation of ordered nanostructures with periodicities around 460 nm. Raman spectroscopy at the excitation wavelengths of 785 and 442 nm was used in order to obtain information about both laser induced chemical and structural modifications, since molecular order and crystallinity in semiconducting polymers have a significant effect on their properties. As a matter of fact, conductive atomic force microscopy (C-AFM), which was used to measure the current through the film thickness, revealed differences in P3HT conductivity between valleys and ridges. Results are discussed in terms of the processes involved in LIPSS formation and related to potential applications.
Authors : M. Martinez-Calderon 1 2, A. Rodriguez 2, A. Dias 1 2, M. Gomez-Aranzadi 1 2, S.M. Olaizola 1 2.
Affiliations : 1 CEIT-IK4 & Tecnun (University of Navarra), Paseo Manuel Lardizabal 15, 20018 San Sebastian, Spain 2 CIC microGUNE, Goiru Kalea 9 Polo Innovacion Garaia, 20500 Arrasate-Mondragon, Spain
Resume : The manufacturing of metal surfaces with highly controllable wetting properties is becoming a very active field in research and engineering. Based on nature examples like rose petals or lotus effect, an effective approach for this purpose is the combination of micro- and nano-structures into hierarchical structures. Traditionally these structures are manufactured by using different types of coatings. However, this can be achieved by only using femtosecond laser ablation in air atmosphere. The first part of this work is a study to determine the microscale modifications produced on a stainless steel alloy (AISI304) surface at high pulse energy, different velocities, and focal distance in order to obtain microstructures with a selected depth of 5 μm and line widths of 30-35 μm. The second part of the work is focused on finding the optima irradiation parameters to obtain the nanostructure pattern. Nanostructures have been defined by means of Laser Induced Periodical Surface Structures (LIPSS) of around 200nm high and a period of 500nm, which constitutes the nanostructure pattern. Finally, dual scale gratings of 50mm2 were fabricated for a range of irradiation parameters (line period, fluence, ablated depth or focal distance) and their effect on the measured contact angle. Combining the micro-pattern with the LIPSS nano-pattern, we have obtained almost superhydrophobic surfaces with measured static contact angles between 130 and 140º, from initial contact angles of 60º.
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Pulsed laser deposition I : R. Serna
Authors : G. Socol1, D. Craciun1, D. Simeone2, S. Behdad3, B. Boesl3, E. Lambers4, C. Himcinschi5, D. Pantelica6, P. Ionescu6, C. Martin7, B. Vasile8, H. Makino9, and V. Craciun1
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Măgurele, Romania; 2DMN/SRMA-LA2M, LRC CARMEN CEA Saclay, France; 3Mechanical and Materials Science Engineering, Florida International University, Miami, USA; 4MAIC, University of Florida, Gainesville, USA; 5Institute of Theoretical Physics, TU Bergakademie Freiberg, Freiberg, Germany; 6Horia Hulubei National Institute for Physics and Nuclear Engineering, Măgurele, Romania; 7Ramapo College of New Jersey, NJ, USA; 8Polytechnic University Bucharest, Romania; 9Research Institute, Kochi University of Technology, Kochi, Japan
Resume : The vast majority of studies about the effects of radiation on the structure and properties of materials used in nuclear reactors or outer space applications have been performed on single crystals or pellets having large grain sizes. However, some specific applications require the use of thin films that are polycrystalline or even nanocrystalline. The effects of radiation on such thin films have only recently been studied, because it is quite difficult to obtain high quality samples. The Pulsed Laser Deposition (PLD) technique is very suitable for this task since it can grow some of the highest quality thin films of almost any materials starting from inexpensive targets. First, it allows the growth of high crystalline quality films at relatively lower substrate temperatures than other techniques. Secondly, by changing the deposition parameters, films possessing different chemical compositions and/or structures could be easily obtained. Thirdly, the surface morphology of the deposited films is very smooth, allowing for the use of characterization techniques such as X-ray reflectivity, grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy, or nanoindentation that possess depth resolutions of the order of few nm. To illustrate these advantages, results obtained on ZrC, ZrN, and SiC thin films grown on Si substrates by the PLD technique that were ion-irradiated at room temperature by 800 keV Ar ions will be presented.
Authors : Cristian Ursu (1), Tudor Coman (2), Elena Laura Ursu (1), Daniel Timpu (1), Mihaela Olaru (1)
Affiliations : (1) "Petru Poni" Institute of Macromolecular Chemistry, Iasi, Romania; (2) Gheorghe Asachi Technical University of Iasi, Romania
Resume : Al-doped ZnO (AZO) thin films with uncommon (110) orientation are obtained on amorphous substrates (glass and polysulfone) through Sequential Pulsed Laser Deposition technique from metallic targets at low substrate temperature (below 100°C). The structural, optical and electrical properties are investigated systematically depending on the oxygen deposition pressure (1 to 10 Pa) and doping concentration (≤ 4.4% at.). For AZO/glass samples we notice a change of the growing mode from (002) preferential orientation to an uncommon (110) preferential orientation through a combined effect of doping concentration and deposition pressure. This transition is accompanied by a change of the morphology (a granular structure with a decreasing density as the (110) peak become dominant), band gap widens (up to 3.88 eV) and electrical resistivity drops (~1x10^-3 Ωcm). As it is well known, for a ZnO material with a wurtzite structure spontaneous and strain induced polarization generate electric fields along the c axis causing a decrease of the quantum efficiency. Therefore, materials for which the c axis is in line with the films surface could be used for light emitting devices (OLEDs) with improved properties. For this reason, we performed AZO thin films deposition on polysulfone substrate to be used as anod for flexible OLEDs. We currently investigate the mechanism responsible for the (002) phase suppression and (110) phase growth for both AZO/glass and AZO/polymer deposited samples.
Authors : A. Mariscal(1), A. Quesada(2), I. Camps(1), J.F. Fernández(2), R. Serna(1)
Affiliations : (1) Laser Processing Group, Instituto de Óptica, CSIC, Serrano 121, 28006 Madrid, Spain; (2) Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Kelsen 5, Madrid 28049, Spain
Resume : Europium oxide films have received large attraction for their use in the fields of microelectronics, spintronics, magnetism and photonics. The fabrication of crystalline high quality pure Eu-oxide thin films is challenging, and growth under oxide gas environment and high temperature processing are usually necessary. However, such processing can lead to the formation of Eu-silicides when Si substrates are used . In this work, we report the preparation of Eu-oxide thin films (200 nm) in vacuum by pulsed laser deposition at room temperature on Si substrates. For deposition an ArF laser (193 nm) was focused on a pure sintered Europium oxide bulk target. In order to study the possible reaction of the Eu-oxide film with the Si substrate films with and without an amorphous Al2O3 buffer layer were deposited. Post-deposition annealing treatments where performed under different conditions. As result, according to the analysis of Raman and X-ray Diffraction (XRD) measurements, crystalline films are formed where both cubic and monoclinic phases can be identified. No silicide formations have been seen. Photoluminescence has been studied under laser excitation at 355 nm. All the films show intense and narrow peaks that are attributed to the intra 4f-transitions of Eu3+ ion in a crystalline host. However, clearly different emission spectra are observed as a function of the specific crystalline phases present. Changes in the magnetic hyperfine 5D0 7F0 transition at 612 nm confirms the crystal field effect and its influence over energy level splitting. The relationship of the photoluminescence emission spectra and the crystal structure will be discussed, as well as the possibility of the reduction of the Eu oxidation state.  G. Bellochi et al., Optics Express 20, 5501 (2012)
Authors : G. Bulai1, V. Nica1, B. Chazallon2, S. Gurlui1, C. Focsa2
Affiliations : 1Faculty of Physics, Alexandru Ioan Cuza University, 700506 Iasi, Romania; 2Laboratoire de Physique des Lasers, Atomes et Molécules (UMR CNRS 8523), Université Lille 1 Sciences et Technologies, 59655 Villeneuve d'Ascq cedex, France
Resume : Ferrites are important magnetic materials with wide application area in current and emerging technologies. Within this class of materials, cobalt ferrite presents the highest magnetostrictive response due to which many sensors, actuators and magnetoelectric composites use this material as active component. Based on the large Faraday effect in the 700800 and 400500 nm spectral ranges, cobalt ferrite is considered as a possible alternative for magneto-optical (MO) devices. Among other effects, rare earth ions are reported to lower the Curie temperature and increase the MO response when present in ferrite structures. The RE substitution can also decrease the grain size, which is an important factor in low noise media. The aim of our study is to analyze the influence of rare earth substitution and deposition conditions on the structural, chemical, optical and magnetic properties of cobalt ferrite thin films. In this context CoFe1.8RE0.2O4 (RE=Gd, Dy, La) thin films were grown in different conditions by Pulsed Laser Deposition. The varied experimental parameters were target-substrate distance, laser fluence, deposition time and substrate type and temperature. The presence of the RE with large ionic radii determined a distortion of the spinel structure. The magnetic measurements revealed an increased magnetization for the CoFe1.8Gd0.2O4 thin film deposited at 400oC and while the La doped sample presented lower magnetization value.
Authors : N. Hildenbrand, J.M. Dekkers, A. Janssens
Affiliations : SolMateS B.V.
Resume : New materials are required in order to meet upcoming technology nodes or to progress beyond Moore. It is well known that Pulsed Laser Deposition (PLD) is a very flexible and versatile technique allowing fast optimization of new thin film materials. Moreover PLD is superior above other deposition technologies for the stabilization of volatile elements and nucleation of complex oxide material systems. However, mainly because of the sample size, the developed materials and processes in PLD research tools only just make it into demonstrator devices. In order to make it into commercial applications, next generation PLD equipment is needed to bridge the gap between demonstrator and the prototype pilot production stages. The new SolMateS R&D platform is the next step beyond fundamental (PLD) research. The reliable hardware is flexible for fast process optimization and allows uniform thin film deposition up to 200 mm diameter with high reproducibility. The automated software ensures easy operation and stable performance. The small footprint makes it very easy to attach it to an existing PLD beam path in the research facility. Since process recipes can be transferred directly to SolMateS PLD production equipment it is the ultimate valorization of thin film research. The PLD R&D platform is the missing link between lab and fab. The first SolMateS PLD production platform is installed in the field in 2013. This tool is the ultimate proof that PLD has now reached the maturity level of High Volume Manufacturing (HVM). This next generation deposition system is suitable for development and (pilot-) production purposes. It is designed for stability, reliability and low maintenance. Equipped with automated wafer handling it offers high run-to-run consistency at commercial throughput and yield. The PLD production platform accelerates the entry of new materials into commercial products. In this contribution the latest performance and specifications of the SolMateS PLD platforms are addressed. Data on stability and reproducibility of wafer scale deposition of piezoelectric Pb(Zr,Ti)O3 (PZT) thin films with excellent properties will be presented. Furthermore, performances and applications of Indium Tin Oxide and Aluminum Oxide thin films deposited with qualified processes will be shown.
Authors : Angela De Bonis1, Antonio Santagata2, Debora Palmieri1, Agostino Galasso1, Roberto Teghil1
Affiliations : 1. Dipartimento di Scienze, Università della Basilicata, Viale dellAteneo Lucano, 10 85100 Potenza, Italy 2. CNR-ISM, U.O.S di Potenza,Zona Industriale di Tito, 85050 Tito Scalo (PZ), Italy
Resume : Nanosized materials have attracted scientific and technological interest over the recent years due to the size dependent properties that can vary considerably from those of the bulk material. In particular, for semiconductor nanocrystals this allows adjustment of absorption and emission properties. GaAs is one of the most important IIIV semiconductors that finds wide applications in electronic industry1. GaAs nanoparticles present large energy bandgap and a large exciton Bohr radius2 so that the quantum confinement effect is pronounced also for relatively big nanoparticles. This allows tuning of the band gap of the nanocrystals across the visible spectrum and makes nanocrystalline GaAs siutable for various applications. GaAs nanocrystals have been obtained both by chemical and physical techniques. We used the Laser Ablation in Liquid technique since it presents some advantages and can be applied for the preparation of colloidal semiconductor solutions. We have investigated the ablation of a GaAs crystalline target in acetone by two laser sources (Nd:glass 527nm, 250fs and 10 Hz and Nd:YAG 532nm, 7ns and 10Hz) with the aim of compare the effect of pulse duration on the physical and chemical processes involved during the ablation and, consequently, on the obtained nanoparticles properties. The ablation process has been studied both by shadowgraphic technique and optical emission spectroscopy and the obtained products have been characterized by transmission electron and scanning electron microscopies, by micro-Raman spectroscopy and X-ray diffraction. 1. A. Bar-Lev, Semiconductors and Electronic Devices, 2nd edn., Prentice Hall, New York (1984). 2. Y. Fu, M. Willander, E. L. Ivchenko, Superlattices Microstruct. 27, 255 (2000).
Authors : Oleksandr Gavrylyuk, Oleksandr Semchuk, Bogdan Lytovchenko
Affiliations : O.Chuyko Institute of Surface Chemistry NAS of Ukraine
Resume : The processing of SiOx film with the typical thermal annealing is not localized process and can lead during annealing to the destruction of the electronic circuits components that are on the same substrate. Only recently, for the formation of nc-Si in SiOx film, the laser annealing was first used. For efficient use of nanostructures in silicon electronics it is necessary to perform the comprehensive theoretical and experimental study of the laser annealing process of non-stoichiometric SiOx films. In this paper, advancement of temperature profiles is analyzed in a non-stoichiometric film SiOx To simulate the temperature profile in the corresponding film used the following laser parameters: pulse duration 10 ns, the intensity of the laser beam is varied in the range of 14 ? 52 МW/сm2. The distribution of the temperature field in the film during its heated single laser beam described nonstationary heat equation, which is solved the numerical by finite element method.It is shown that the smaller the duration of the laser pulse, the greater the local temperature (temperature at the time of contact of pulse with the surface). Therefore, the pulse width is a parameter that can adjust the temperature on the surface of the sample and therefore further temperature distribution in the sample volume.
Authors : Thibault J.-Y. Derrien (1, 3), Tatiana E. Itina (1), Elena Silaeva (2), Angela Vella (2), Laurent Arnoldi (2), Bernard Deconihout (2)
Affiliations : (1) Hubert Curien Laboratory (LabHC), UMR CNRS 5516 - Jean-Monnet University. Bat. F, 18 rue du Professeur Benoit Lauras, 42000 Saint-Etienne, France. (2) Groupe de Physique des Matériaux UMR CNRS 6634, CORIA UMR 6614 - UFR Sciences Site du Madrillet, Avenue de lUniversité́ - B.P. 12 76801 Saint Etienne du Rouvray CEDEX, France (3) HiLASE Centre, Institute of Physics, Academy of Science of the Czech Republic, Za Radnicí 828 828/5, 25241 Dolní Břeany, Czech Republic
Resume : Laser-assisted atomic probe tomography is a versatile tool to analyze chemical composition of different materials (metals, semiconductors, dielectrics) with an atomic resolution. A solid tip is placed in a strong DC field and is subjected to rather weak ultra-short laser pulses. As a result, surface atoms are evaporated towards a detector one by one. For metals, evaporation is triggered by thermal heating of the tip apex. For oxides, additional high field effects explain the ultrafast contribution in Time Of Flight (TOF) observations. However, a second peak is usually obtained for semiconductors, and its origin remained unexplained. In this study, a three-temperature 3D model is applied to a silicon tip irradiated by femtosecond laser. Optical absorption of the laser pulse by the sub-wavelength tip reveals a strong enhancement of the laser field inside the tip, highly dependent to the tip geometry and to the laser wavelength. The numerical calculations demonstrate that inhomogeneous laser energy coupling with silicon lattice followed by energy diffusion result in a delayed heating of the apex, explaining the second peak observed in Time Of Flight measurements. The energy balance reveals that contribution of the Auger recombination to the heating depends on the laser wavelength and explains the experimental results.
Authors : Ru.G. Nikov*1, N.N. Nedyalkov1, P.A. Atanasov1, D. Hirsch2, B. Rauschenbach2
Affiliations : 1Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko chaussee 72, Sofia 1784, Bulgaria 2Leibniz Institute of Surface Modification (IOM), Permoserstrasse 15, D-04318 Leipzig, Germany
Resume : The paper presents results on laser nanostructuring of Ag thin films. The thin films are deposited on glass substrates by pulsed laser deposition technology. Then the films are annealed by nanosecond laser pulses delivered by Nd:YAG laser system operated at λ = 355 nm. The film modification is studied as a function of the film thickness and the parameters of the laser irradiation as pulse number and laser fluence. In order to estimate the influence of the environment on the characteristics of the fabricated structures the Ag films are annealed in different surrounding media: water, air and vacuum. It is found that at certain conditions the laser treatment may lead to decomposition of the films into a monolayer of nanoparticles with narrow size distribution. The optical properties of the fabricated nanostructures are investigated on the basis of transmission spectra taken by optical spectrometer. In the measured spectra plasmon resonance band is observed as its shape and position vary depending on the processing conditions. The fabricated structures are covered with Rhodamine 6G and tested as active substrates for Surface Enhanced Raman Spectroscopy (SERS).
Authors : P. A. Atanasov1*, N. E. Stankova1, N. N. Nedyalkov1, T. R. Stoyanchov1, Ru. G. Nikov1, J. W. Gerlach2, D. Hirsch2, B. Rauschenbach2
Affiliations : 1Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Boul., Sofia 1784, Bulgaria. 2Leibniz Institute of Surface Modification (IOM), Permoserstrasse 15, D-04318 Leipzig, Germany
Resume : Medical grade polydimethylsiloxane (PDMS) elastomer is a widely used biomaterial in medicine and high-tech devises because of its remarkable properties: mechanical flexibility and stability; high dielectric constant and breakdown field; optical transparency in the ultraviolet (UV) visible (VIS) spectral regions; high biocompatibility and biostability; simple and inexpensive fabrication. High definition tracks and electrodes can be accomplished by UV or VIS ns- or fs-laser pulse processing with subsequent metallization in order to get alterations of the chemical composition and structural morphology of the ablated traces. The importance of knowing the changes of the morphology, structure and chemical properties of the laser processed material will help to understand nature of the laser - matter interaction. In this work we present experimental results on change of the morphology, chemical composition and structure of UV, VIS and IR ns-laser processing. Laser processing of medical grade PDMS elastomer is accomplished using fundamental (λ = 1.06 µm), 2nd HG (λ = 532 nm) and 4th HG (λ = 266 nm) of Q-switched Nd:YAG laser (pulse duration τ=15 ns and rep rate of 10 Hz). The as-processed material is studied by XRD, SEM and µ-Raman analyses in order to get information for the influence of different processing parameters as laser wavelength, fluence and subsequent pulses on the surface morphology, crystallinity and chemical changing.
Authors : N.Nedyalkov1, M. Koleva1, R. Nikov1, P. Atanasov1, Y. Nakajima2, M. Terakawa2
Affiliations : 1Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784, Bulgaria 2Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi Kohoku-ku, Yokohama-shi Kanagawa-ken, 223-8522, Japan
Resume : In this work results on laser processing of zinc oxide thin films deposited on different substrates are presented. ZnO films are deposited by classical PLD method in oxygen atmosphere on metal and quartz substrates. The produced films are then processed by nanosecond pulses delivered by Nd:YAG laser system. The laser processing parameters and the film thickness are varied and their influence on the fabricated structures is presented. The film morphology after the laser treatment strongly depends on the substrate. It is shown that at certain conditions the laser treatment of the film deposited on metal substrate leads to formation of a discrete nanostructure, composed of spherical like nanoparticles. The structure, morphology and optical properties of the fabricated samples are presented and discussed. The demonstrated method is an alternative way for fabrication of ZnO nanostructures with application in solar cell technology, sensor devise fabrication and optoelectronics.
Authors : Thibault J.-Y. Derrien (1,3), Robert Koter (1), Jörg Krüger (1), Sandra Höhm (2), Arkadi Rosenfeld (2), Jörn Bonse (1)
Affiliations : (1) BAM Bundesanstalt für Materialforschung und prüfung, Unter den Eichen 87, D-12205 Berlin, Germany; (2) Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489; Berlin, Germany; (3) HiLASE Centre, Institute of Physics, Academy of Science of the Czech Republic, Za Radnicí 828 828/5, 25241 Dolní Břeany, Czech Republic.
Resume : The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of silicon by multiple linearly polarized 30 fs laser pulses (wavelength of 790 nm) is studied in air and water environment. The LIPSS surface morphologies are characterized by scanning electron microscopy and their spatial periods are quantified by two-dimensional Fourier analyses. It is demonstrated that the irradiation environment significantly influences the periodicity of the LIPSS. In air, low-spatial frequency LIPSS (LSFL) were found with periods somewhat smaller than the laser wavelength (70% of laser wavelength) and an orientation perpendicular to the laser polarization. In contrast, for laser processing in water, a reduced ablation threshold and LIPSS with approximately five times smaller periods (15% of laser wavelength) were observed in the same direction as in air. A thin-film based surface plasmon polariton model successfully describes the tremendously reduced LIPSS periods in water.
Authors : P. Dubček1, B. Pivac1, N. Radić1, N. Krstulović2 and M. Bićan2
Affiliations : 1 Rudjer Boskovic Institute, Bijenicka 54, HR-10000 Zagreb, Croatia 2 Institute for Physics, Bijenicka 46, HR-10000 Zagreb, Croatia
Resume : The quest for light absorption enhancement in future photovoltaics is relying on the surface plasmon resonance too. This can be realized by aluminium nanoparticles application. When placed close to the photoactive layer of bulk of the heterojunction, they scatter light heavily into the optically active layer, and thus enhance the efficiency of photovoltaic devices. For such an application, a good control of nanoparticles sizes and space distribution is a must. The control of sizes via thermal treatment sometimes calls for prohibitively high annealing temperatures, that tend to damage the heterojunction structure itself. Therefore, laser dewetting is an alternative mode of creating these plasmonic nanoparticles, while avoiding the need for excessive temperatures in the thermal treatment. Here we report on aluminium nanoparticle production by laser induced dewetting. Initially smooth Al films, produced by magnetron sputtering on monocrystalline silicon at room temperature were treated by nanosecond pulsed infra-red and ultra-violet laser. The nominal film thickness was ranged from 10 to 20nm, while the number of pulses varied from 1000 to 10 000, and single pulse energy fluence from 70 to 200mJ/cm2. Sharp size distribution, that is suitable for application, has been obtained for optimized combination of pulse number and fluence.
Authors : M.E. Koleva1, N.N. Nedyalkov1, P.A. Atanasov1, B. Rauschenbach2, J.W. Gerlach2, D. Hirsch2, A. Prager2
Affiliations : 1Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee blvd., Sofia 1784, Bulgaria 2 Leibniz Institute of Surface Modification (IOM), Permoserstrasse15, D-04318 Leipzig, Germany
Resume : The nanostructures of porous ZnO are subject of research interest, due to their specific structure with high surface to volume ratio that may produce peculiar properties for use in sensing and optoelectronics applications. On the other hand, a large electromagnetic field enhancement originated from the localized surface plasmon resonance of noble metal nanostructures is employed in various applications. This research is focused on investigation of the coupled plasmonic-semiconducting nanomaterials for photoluminescence emission enhancement and SERS applications. The produced porous ZnO nanostructures with plasmonic Ag inclusions exhibit interesting and promising results. These heterostructured nanocomposites hold a great potential in applications such as a light emitting devices and SERS substrates. We demonstrate a two-step laser method for incorporating of plasmonic Ag nanoparticles into porous metaloxide semiconductors. The synthesis is carried out by Nd:YAG laser and consisted of PLD from mosaic ZnO/Ag target and post deposition fragmentation by laser annealing. The produced porous ZnO nanostructures with plasmonic AgNPs exhibited interesting and promising results. The phase structure, chemical composition and morphology were analyzed by XRD, XPS and HRSEM. The plasmon resonance absorption was confirmed by optical transmission spectroscopy in the spectral range of 200-800 nm. The SERS activity and PL emission enhancement of the composites were studied.
Authors : S. Höhm (1), M. Herzlieb (1), A. Rosenfeld (1), J. Krüger (2), J. Bonse (2)
Affiliations : (1) Max-Born-Institut, Max-Born-Straße 2a, D-12489 Berlin, Germany; (2) BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin, Germany
Resume : In order to address the dynamics and physical mechanisms of LIPSS formation for three different classes of materials (metals, semiconductors, and dielectrics), two-color double-fs-pulse experiments were performed on titanium, silicon and fused silica. For that purpose a Mach-Zehnder interferometer generated polarization controlled (parallel or cross-polarized) double-pulse sequences at 400 and 800 nm wavelength, with inter-pulse delays up to a few picoseconds. Multiple of these two-color double-pulse sequences were collinearly focused by a spherical mirror to the sample surfaces. The fluence of each individual pulse (400 & 800 nm) was always kept below its respective ablation threshold and only the joint action of both pulses lead to the formation of LIPSS. Their resulting characteristics (periods, areas) were analyzed by scanning electron microscopy. The periods along with the LIPSS orientation allow a clear identification of the pulse which dominates the energy coupling to the material. For strong absorbing materials (silicon, titanium), a wavelength-dependent plasmonic mechanism can explain the delay-dependence of the LIPSS. In contrast, for dielectrics (fused silica) the first pulse always dominates the energy deposition and LIPSS orientation, supporting a non-plasmonic formation scenario. For all materials, these two-color experiments confirm the importance of the ultrafast energy deposition stage for LIPSS formation.
Authors : J. Bonse (1), S. Höhm (2), R. Koter (1), D. Spaltmann (1), M. Hartelt (1), S. Pentzien (1), S. Marschner (2), A. Mermillod-Blondin (2), A. Rosenfeld (2), J. Krüger (1)
Affiliations : (1) BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin, Germany; (2) Max-Born-Institut, Max-Born-Straße 2a, D-12489 Berlin, Germany
Resume : Laser-induced periodic surface structures (LIPSS) were generated on pure titanium and titanium alloy (Ti6Al4V) surfaces upon irradiation with multiple linear polarized femtosecond laser pulses in air (30 fs duration, 790 nm wavelength, 1 kHz pulse repetition rate, Gaussian beam shape). The conditions were optimized in a sample-scanning geometry for the processing of large surface areas covered homogeneously by two different types of nanostructures, i.e., low-spatial frequency LIPSS (LSFL) with periods around 600 nm and high-spatial frequency LIPSS (HSFL) having periods around 100 nm. For both types of nanostructures the tribological performance was characterized under reciprocating sliding condition against a ball of hardened steel at 1 Hz using different lubricants. After 1000 cycles, the corresponding wear tracks were characterized by optical and electron microscopy. For specific conditions, the wear was strongly reduced and the nanostructures (LSFL) endured the tribological treatment. Simultaneously, a significant reduction of the friction coefficient was observed, indicating the potential benefit of laser surface structuring for tribological applications. For optimization, the spatially Gaussian shaped beam used for the laser processing was transformed into a Top-Hat distribution by using a spatial light modulator (0.1 kHz). The tribological performance of samples processed with a Top-Hat beam is compared to that obtained with a Gaussian laser beam.
Authors : A. Nikolov1, T. Koutzarova1, N. Nedyalkov1, R.Nikov1, S. Kolev1, P. Peneva1, P. Atanasov1, D. Karashanova2, D. Kovacheva3
Affiliations : 1 Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784, Bulgaria 2 Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, Building 109, 1113 Sofia, Bulgaria 3 Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., bld. 11, 1113 Sofia, Bulgaria
Resume : We present results on fabrication and characterization of Sr3Co2Fe24O41 nanostructures in colloid. Nanosecond laser ablation in liquid is used as a method for sample preparation. The target is fabricated from microparticles obtained by sol-gel auto-combustion. The powders synthesized are then pressed and annealed at a high temperature for a certain time and subsequently quenched rapidly to room temperature. The target is ablated in double distilled water using a Nd:YAG laser system. The laser wavelength (the fundamental, second and third harmonics) and fluence are varied in order to estimate their influence on the morphology of the nanostructures produced. The stability is also investigated of the colloids during their aging. To study the colloids optical properties, the optical transmission is measured in the near UV and visible regions. The shape of the nanostructures and their size distribution are visualized by using SEM and TEM analysis. XRD, SAED and HRTEM are utilized to examine the material phases of the nanostructures obtained. The results presented could be used for designing nanostructures fabrication technologies with parameters appropriate for application in the fields of spintronics and biomedicine.
Authors : N. E. Stankova1, P. A. Atanasov1, N. N. Nedyalkov1, T. R. Stoyanchov1, R. G. Nikov1, Ru. G. Nikov1, N. Fukata2
Affiliations : 1 Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Boul., Sofia 1784, Bulgaria 2 International Center for Materials for NanoArchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1Namiki, Tsikuba 305-0044, Japan
Resume : Polydimethylsiloxane (PDMS) elastomer is a widely used material in medicine and high-tech devises because of its mechanical flexibility and stability, high dielectric constant, optical transparency from the ultraviolet (UV) to near infrared (IR) spectral region, high biocompatibility and biostability, simple and inexpensive fabrication. Despite the low absorption of the native PDMS for UV, VIS and near IR wavelengths, the laser treatment is enhanced by an incubation process. The latter occurs as a result of the multipulse processing. In such a way, the initial absorbed laser fluence is valid only for the first laser pulse hitting the material. The next consecutive pulses interact with the material with changed optical properties. The importance of knowing the exact optical properties of the material will help to the description of the interaction between laser radiation and material as well as modeling of the process. In this work we present experimental results on gradual change of the optical properties during UV, VIS and IR ns-laser processing. Laser processing of medical grade PDMS elastomer is accomplished using fundamental (λ = 1006 nm), 2nd HG (λ = 532 nm) and 4th HG (λ = 266 nm) of Q-switched Nd:YAG laser (pulse duration τ=15 ns and rep rate of 10 Hz). The influence of different processing parameters as laser wavelength, fluence and number of the subsequent pulses on the optical absorption and surface morphology are studied.
Authors : Camille Hairaye, Manuel Flury, Thierry Engel, Frédéric Mermet, Joël Fontaine
Affiliations : IREPA LASER, Parc dInnovation, 67400 Illkirch, France. Laboratoire des Sciences de lIngénieur, de lInformatique et de lImagerie (ICube), UDS-CNRS-INSA-ENGEES, 300 bd Sébastien Brant, CS 10413, 67412 Illkirch, France
Resume : Surface texturing by ultrashort laser pulses, in the range of hundreds of femtoseconds, is a simple and fast process that can be used to modify physicochemical properties of the irradiated area. A self-organization of the matter after laser irradiation results in micro- and nano-scaled structures on the sample surface. Surface specifications rely greatly on the control of key-parameters of the laser such as wavelength, laser fluence, polarization, spot overlap or number of impacts. According to the process parameters, structures at two scales are generated, allowing the changing of for instance the visual aspect of the surface or its wetting behaviour. This paper will focus on the generation of self-organized nanostructures known as ripples on a stainless steel sample, and on their characterization using the 2D Fast Fourier Transform technique. Ripples are periodic nanometric structures, assembled according to a preferential direction. In the case of a linear polarized laser beam, both these orientations are perpendicular. By inserting a half-wave plate into the optical path, it is easy to rotate the linear polarization around the optical axis and so modify the direction of the ripples. Characterization of these nanostructures by Scanning Electron Microscopy provides high resolution images, with the advantage that very high spatial frequencies can be reached for the calculation of the 2D Fast Fourier Transform of the periodicity of the ripples.
Authors : N.N.Tarasenka, A.V.Butsen, V.V.Kiris and N.V.Tarasenko
Affiliations : Institute of Physics, National Academy of Sciences of Belarus, 68 Nezalezhnasti Ave., 220072 Minsk, Belarus
Resume : Pulsed laser ablation technique in liquids (PLAL) is one of the hot topics of contemporary research in the field of nanotechnology. In the most cases PLAL is used to produce particles of metals and their oxides, and there are relatively few works devoted to the synthesis of composite NPs. Composite systems are of great interest, because their properties generally differ from those of similar single-component structures. In addition, the physical properties of composite particles can be varied by changing their component ratio. In the present paper several approaches of PLAL, for example based on the sequential ablation of different targets in the same solution, simultaneous ablation of combined target, post irradiation method as well as a combination of different approaches have been developed to prepare bimetallic nanoparticles (Ag-Au, Ag-Cu) and particles of complex composition, such as Ag-ZnO nanocomposites and magnetic nanoscale compounds and alloys of gadolinium. By controlling laser irradiation time and laser energy different structures like core-shell, chain-like structure and hollow particles have been synthesized. The effect of several polymers like PVP, PVA and polysaccharides on the morphology and size stabilization of the generated nanostructures in the laser ablation and the secondary laser irradiation processes has been investigated. The possibility of application of the synthesized nanostructures in sensing, optics and biomedicine will be discussed.
Authors : J. Penide (1), A. Riveiro (1), R. Soto (1), M. Boutinguiza (1), F. Arias-González (1), J. del Val (1), R. Comesaña (2), F. Lusquiños (1), F. Quintero (1), E. García (3), J. Pou (1)
Affiliations : (1) Applied Physics Department, EEI, University of Vigo, Vigo, Spain; (2) Materials Eng., Applied Mech. and Construction Dpt., EEI, University of Vigo, Vigo, Spain; (3) Cupa Innovación, S.L. Vigo, Spain
Resume : Slate is a natural rock that has a very important presence in European buildings. It is usually employed in roofs, façades and for tiling. In spite of this broad use, production process of slate tiles is not optimized. An important quantity of slate from the quarry is wasted during the manufacturing of the final product. Therefore, companies are looking for new and improved methods capable of enhance their efficiency in order to increase productivity and reduce costs. Drilling is an important part of this manufacturing process. Conventional tools usually cause breaking of the slate tiles, so even a higher quantity of material is wasted. In this sense, laser is a very suitable tool to produce holes in this material since it does not generate any mechanical stresses on the workpiece. In this work we present a comprehensive experimental study on laser microdrilling of slate tiles. We employed a Design of Experiments (DoE) methodology to establish the influence of the most important processing parameters on the diameter of the holes. We also employed a Response Surface methodology to determine non-linear behaviors and the interdependence of these processing parameters on the geometry and quality of holes. Finally, we were able to produce holes with less than 100 microns in diameter, avoiding any fracture, and with a processing time of 45 ms per hole.
Authors : C. Constantinescu, D.L.N. Kallepalli, P. Delaporte, O. Uteza, D. Grojo
Affiliations : Aix-Marseille Universite / CNRS, Laboratoire LP3 (UMR 7341), F-13288 Marseille, France
Resume : Long-range arrays of well-shaped metal nanostructures have been fabricated by a hybrid methodology, i.e. using Langmuir microsphere films and laser-assisted dewetting. As the initial step, we use colloidal lithography. Monolayers of 1-5 μm polystyrene microspheres are used as masks to pattern the surface of quartz or silicon substrates, typically in the order of cm², with a thermally evaporated Ag thin film of controlled thickness. When removing the spheres by physico-chemical means, the deposition directly leaves behind arrays of nanosize silver triangles / prisms that can be furthermore laser processed. Thus, by using two lasers (355-nm wavelength, 50-ps duration and 193-nm wavelength, 15-ns duration) for the metal dewetting, we aim to control the shape of the deposited nanostructures. A detailed study is presented here on the reshaping of these nanostructures by laser annealing. In previous work we prepared nanodot arrays, by using monolayers of spheres as microlenses, and by microsphere-assisted laser fabricated mesoporous membranes. Such hybrid methodology will enlarge the panel of available microsphere-assisted technologies to prepare surface nanomaterials.
Authors : A. Riveiro (1), R. Soto (1), J. del Val (1), R. Comesaña (2), M. Boutinguiza (1), F. Quintero (1), F. Lusquiños (1), J. Pou (1)
Affiliations : (1) Applied Physics Department, University of Vigo EEI, Lagoas-Marcosende, 9. Vigo, 36310, Spain; (2) Materials Eng., Applied Mech., and Construction Dpt., Universidade de Vigo, EEI Vigo, Spain
Resume : The effects of surface topography are widely recognized as a key factor on the implant osseointegration. For example, hydrophilic surfaces seem to favour the interactions of an implant with cells as compared to hydrophobic surfaces. On the other hand, the increment of the roughness of an implant improves its mechanical fixation. Different techniques, such as sandblasting, plasma treatment, ion implantation, electrolytic coating, laser treatments, etc., have been studied to engineer the surface properties of biomaterials with the aim to improve their biological surface properties. The final objective of these treatments is the promotion of bone formation, confer better stability during the healing process, and in consequence allowing a faster loading of the implant. In this context, laser texturing offers a high versatility to tailor the surface properties of a biomaterial to improve their osseointegration. Laser treatments are highly localized, productive, flexible in materials and geometries, and can be performed at atmospheric pressure. In this work, we have studied the topographical modification of polypropylene (PP) which has been laser textured by Nd:YVO4 nanosecond lasers emitting at three different wavelengths of 1064, 532, and 355 nm. The influence of the laser processing parameters on the surface modification of PP has been investigated by means of statistically designed experiments. Processing parameters relevant to the process were identified and their influence on the surface texturing determined. Furthermore, most adequate processing conditions to increase the roughness and wettability, the main parameters affecting cell adhesion characteristics of implants, were also determined.
Authors : Daniel E. Martínez-Tong1, Álvaro Rodríguez-Rodríguez1, Aurora Nogales1, Mari Cruz García-Gutiérrez1, Tiberio A. Ezquerra1, Esther Rebollar2
Affiliations : 1Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, Madrid 28006, Spain; 2Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 119, Madrid 28006, Spain
Resume : Information storage in organic materials is an essential aspect towards the development of organic electronic systems. Organic memory devices have focused attention on ferroelectric polymers as active storage components, where the poly(vinylidene fluoride) (PVDF) and its copolymer with trifluoro ethylene P(VDF-TrFE) are the most used. Nanopatterning can play an important role to enhance information density by controlling molecular orientation. Here, we report on the formation of laser induced periodic surface structures (LIPSS) on P(VDF-TrFE) thin films upon irradiation with the second harmonic of a Nd:YAG laser (532 nm, pulse duration 8 ns). Although P(VDF-TrFE) does not absorb light in the visible region, LIPSS can be obtained by the preparation of bilayer polymer thin films in which the bottom layer efficiently absorbs at the irradiation wavelength. In this case, poly(3-hexyl thiophene) (P3HT), which is a semiconducting polymer, was used. The ferroelectric nature of the structured bilayer was proven by piezoresponse force microscopy measurements. Ferroelectric hysteresis was found on both pristine and laser structured bilayer. Additionally, it is possible to write ferroelectric information at the nanoscale, and the laser structured bilayer showed an increase in the information storage density of an order of magnitude in comparison to the original bilayer. Results show the potential of laser nanostructuring procedure in order to develop non-volatile organic memory devices.
Authors : Tomas Tamulevičius, Dainius Virganavičius, Linas imatonis, Lukas Ramalis, Sigitas Tamulevičius
Affiliations : Institute of Materials Science of Kaunas University of Technology, K. Barausko St. 59, Kaunas LT-51423, Lithuania
Resume : Conventional lithography techniques used for patterning of reasonable sized areas with sub 100 nm regular features requires expensive hardware or are time consuming. Holographic lithography is one of the most promising techniques for patterning regular structures. Pitch and pattern of the structures depends on the optical setup and laser wavelength where at least 2 laser beams are necessary. Complex pattern geometries can be obtained employing multiple beams or multiple exposures. It is practically the only way of producing 3D structures for visible range photonic applications via parallel exposure. In the current work sub-wavelength pitch structures were patterned in different positive and negative tone photoresist films on silicon employing automated Lloyds mirror interferometer setup and a long coherence length solid state UV laser. In the following step, thin silver films were deposited by electron beam evaporation on inclined samples with the regular structures. Specular reflection from the samples was investigated employing polarized white light angular reflection measurement system. Such structures demonstrated resonant optical response where sharp reflection peaks can be attributed to Woods anomalies, i.e. leaky modes excited in the regular structure, together with a broad absorption peak that can be attributed to the surface plasmon resonance in silver. The structures can be used as diffractive sensor chips in refractometry based in-situ refractive index sensors.
Authors : Jeeyoung Lee, Hyungsuk Min, Yoonseok Oh, Harim Oh, Minseok Seo, Myeongkyu Lee
Affiliations : Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Republic of Korea
Resume : We show that highly conductive Cu films are obtainable from Cu complex ink by laser sintering. The Cu inks, synthesized using Cu formate as a precursor, were spin-coated onto polyimide substrate and scanned by an ultraviolet laser at 355 nm. The blowing of nitrogen gas into the irradiated area prevented the film from being oxidized and a minimum resistivity of 1.70 x 10^-5 ohm cm was obtained. The laser-sintered film, composed mainly of nanorods, exhibited a much tighter structure than the one achieved by the typical thermal process. While the film connectivity and surface coverage became very poor after thermal sintering, laser-sintered films exhibited tightly packed, compact microstructure maintaining a uniform thickness. This made it possible to achieve much lower sheet resistances by laser sintering, especially when the film thickness was less than 1 micrometer.
Authors : F. Caballero-Lucas, C. Florian, J.M. Fernández-Pradas, J.L. Morenza, P. Serra
Affiliations : Departament de Física Aplicada i Òptica, Universitat de Barcelona
Resume : Femtosecond lasers are versatile tools to process transparent materials. Thanks to the non-linear interaction of ultrashort pulses with matter, tightly focused radiation can be absorbed even by materials transparent to the laser wavelength. This can be used in high-resolution bulk processing: the laser beam can penetrate and be absorbed just in a tiny region around the beam waist. However, this behavior poses a serious problem for surface modification. In this case, the radiation would not be absorbed at the surface unless the beam is just focused there. Otherwise, absorption would take place in the bulk leaving the surface unperturbed. Therefore, a strategy to position the laser beam waist on the material surface with high accuracy is essential. We investigate and compare two options to achieve the desired aim: the use of transmittance measurements across the sample and the use of reflectance data, both obtained during z-scans with pulses from a 1027 nm wavelength laser and 450 fs pulse duration. As the beam waist enters the material, a drop in the transmittance is observed while a reflectance peak is detected. With the combination of these observations, it is possible to control the position of the beam waist with respect to the sample surface with high resolution and, thus, attain pure surface modification. In the case of polymethyl-methacrylate (PMMA), this resolution is 1 µm. The results prove that these methods are feasible for submicrometric processing of the surface.
Authors : R.G. Nikov1, A.S. Nikolov1, N.N. Nedyalkov1, P.A. Atanasov1, M.T. Alexandrov2, D.B. Karashanova3
Affiliations : 1Institute of Electronics, Bulgarian Academy of Sciences, Tsarigradsko Chaussee 72, Sofia 1784, Bulgaria 2Institute of Experimental Pathology and Parasitology, Bulgarian Academy of Sciences, G. Bonchev Street, bl. 25, Sofia 1113, Bulgaria 3Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, G. Bonchev Street, bl. 109, Sofia 1113, Bulgaria
Resume : Nanosecond pulsed laser ablation of high purity zinc target immersed in double distilled water is used to fabricate different colloidal zinc oxide (ZnO) nanostructures. The influence of the laser wavelength on the properties of the synthesized ZnO nanostructures was examined. For this purpose three different wavelengths: second (532 nm), third (355 nm) and fourth (266 nm) harmonic of a Nd:YAG laser were used in the experiments. The optical spectra of the fabricated colloids were used to determine the optimal absorption of the zinc oxide nanostructures. This data is utilized to define an optimal laser wavelength that ensures maximal absorption by the already created nanostructures. Laser treatment of already fabricated colloids at this condition was applied to modify efficiently the size distribution of the colloidal nanoparticles. The produced colloidal nanostructure were analyzed by transmission electron microscopy (TEM), X-Ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-visible transmission measurements in order to evaluate their morphology, size distribution, crystalline structure, elemental composition and optical properties. The presented method can be an efficient alternative for fabrication of metal oxide nanostructures with application in biomedicine, photonics and sensor devices.
Authors : F. Stokker-Cheregi, A. Bercea, M. Dinescu, T. Acsente, G. Dinescu
Affiliations : National Institute for Lasers, Plasma and Radiation Physics, 077125 Magurele, Romania
Resume : We investigate the feasibility of using nanosecond laser pulses, at different wavelengths and energies, to remove metal particles having various sizes from different types of surfaces. Our study relates to the broader issues posed by the accumulation of large quantities of tritiated metal powders, due to wall erosion, in next-generation fusion reactors. Previously , we used laser-based methods to create surfaces contaminated with particles obtained from materials that are functionally related to those that will be used in such reactors. The present study capitalizes on our previous knowledge and represents another step forward towards the development of a solution for mobilization, transport and collection of metal powders from contaminated surfaces. We use laser-based techniques to obtain particle contaminated surfaces, which are subsequently treated by using nanosecond laser pulses. We investigate the influence of particle-surface bond strength and particle size on the removal efficiency and threshold.  F. Stokker-Cheregi et al., Digest Journal of Nanomaterials and Biostructures 7, 1569 (2012)
Authors : Katarzyna Grochowska, Katarzyna Siuzdak, Gerard Śliwiński
Affiliations : Centre for Plasma and Laser Engineering, The Szewalski Institute, Polish Academy of Sciences, 14 Fiszera St, 80-231 Gdańsk, Poland
Resume : Recently, substantial interest is observed in utilizing of the plasmonic effect to enhance the electron transfer and electrode conductivity in biosensors based on transparent semiconductor materials such as Indium-Tin-Oxide (ITO). In this work we report the production and characterization of the ITO electrodes functionalized by Au nanoparticle (NP) arrays formed by pulsed laser nanostructuring of gold films. The SEM inspection of modified electrodes reveals the presence of spherical particles of diameters in the range of 40-100 nm and the NP-array geometry can be controlled by selection of the laser processing conditions. It is shown that particle size as well as packing density of the array are important factors which determine the electrode performance. The electrochemical characteristics of the ITO electrodes functionalized by Au NPs when studied in the presence of glucose solution show that the current registered at the oxidation peak rises with increasing glucose concentration markedly higher than in case of bare ITO. The detection limit reaches 20 µM and linear dependence is observed from 0.1 to 40 mM that covers the normal physiological range for the detection of blood sugar. Common interfering species naturally present in the physiological environment (e.g. ascorbic acid) do not reveal observable effects on the glucose detection. KG and KS acknowledge the National Science Centre of Poland for financial support via grants 2012/07/N/ST5/02139 and 2012/07/D/ST5/02269.
Authors : S. Leyder (1), G. Coustillier (1), B. Dunne (2), P. Delaporte
Affiliations : (1) Aix-Marseille University, CNRS, 163 avenue de Luminy-UMR 7341, Case 917, 13288 Marseille cedex 9 FRANCE ; (2) NEXCIS photovoltaïc technology, 240 avenue Olivier Perroy, 13790 Rousset cedex FRANCE
Resume : Direct laser scribing of solar cell has received considerable interest in recent years due to the non-contact, high resolution and high speed nature of the technique that make it suitable for industrial applications. This method is especially suitable for the patterning of thin film solar cells into modules by selective laser ablation of some layers of the stack. In this study, a femtosecond laser beam is focused at the surface of CIGS solar cell to achieve the selective ablation of the upper layers. We determine optimized process conditions for the selective ablation of the Transparent Conductive Oxide (TCO) layer for various thicknesses to perform a p3-type ablation with very limited degradation of the electrical properties of the solar cell. Similar experiments have been performed for the laser patterning of the CIGS film. The morphological and electrical characterization highlight the importance of using femtosecond laser pulses with minimized energy density to limit thermal effects on the ablation edges which lead to a reduction of the module efficiency. The different ablation mechanisms involved are discussed as a function of the layer properties. The results of this study demonstrate the ability of the laser process to selectively pattern the thin film solar cell with minimal loss of solar cell performance.
Authors : A. Santagata (1), A. Guarnaccio (1)*, D. Pietrangeli (1), Á. Szegedi (2), J. Valyon (2), A. De Stefanis (3), A. De Bonis (1,4), R. Teghil (4), M. Sansone (4), D. Mollica (1), G.P. Parisi (1)
Affiliations : (1) Institute of Structure of Matter, U.O.S. Tito Scalo, Potenza Research Area - CNR, C/da S. Loja, 85050 Tito Scalo (PZ), Italy (2) Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, 1117 Budapest, Magyar tudósok körútja 2, Hungary (3) Institute of Structure of Matter, Rome Research Area - CNR, Via Salaria Km 29, 300, Monterotondo, 00016 Rome, Italy (4) Università degli Studi della Basilicata, Dipartimento di Scienze, Via dell'Ateneo Lucano, 10 - 85100 Potenza, Italy
Resume : Ultra-short pulsed laser ablation of materials in liquid is a versatile technique for nanoparticles production. In the present work this approach has been used for producing in situ silver-silica core-shell nanoparticles during the process of silver ablation in stirred water suspensions of hexagonally ordered silica nanoporous (SBA-15 and MCM-41) materials. The nanocomposite suspensions obtained have been characterized by UV-vis spectroscopy and the observed features have been related to the components of the colloidal solution as well as to the laser ablation process parameters used. In order to obtain more detailed information about the nanocomposite generated materials TEM morphologic characterizations have been performed as well. Significant amount of small sized silver-core nanoparticles have been detected in both studied nanoporous silica structures and Ag-silica core-shell nanocomposites obtained within the nanoporous silica colloidal solutions have been also evidenced. The dispersion of the nanocomposites has been related to the extent of damage induced in the nanoporous silica structure during the ablation procedure here adopted. High stability of the produced silver-silica core-shell nanocomposites has been observed after a certain period from the production. We also evidenced that the choice of the ordered nanoporous silica material, SBA-15 or MCM-41, can affect the silica shell thickness as well as size distribution and their field of potential applications.
Authors : Orman Gref1, Moshe Weizman2, Holger Rhein3, Onno Gabriel3, Rutger Schlatmann2, Christian Boit1, Felice Friedrich1
Affiliations : 1 Technische Universität Berlin, Semiconductor Devices Division / PVcomB, Sekr. E4, Einsteinufer 19, 10587 Berlin, Germany 2 University of Applied Sciences (HTW) Berlin / PVcomB, Schwarzschildstr. 3, 12489 Berlin, Germany 3 Helmholtz-Zentrum Berlin für Materialien und Energie (HZB), Silicon Photovoltaics / PVcomB, Kekulestr. 5, 12489 Berlin, Germany
Resume : Laser-firing of metal on semiconductor layers is a well-known method to reduce the contact resistance of this layer system. Recently, it has been shown that liquid phase crystallized (LPC) solar cells on glass prepared with a laser-fired rear-side point contact scheme can gain significantly in efficiency. In order to develop a robust, scalable and cost-effective contacting technique, however, the laser process still needs to be optimized to the properties of the materials. We present a conductive atomic force microscopy (c-AFM) study on such laser-fired contacts that contains data acquired simultaneously on both the topography and the conductivity of the samples. A test structure consisting of an 100nm aluminum layer on a typical KOH structured p-type LPC polycrystalline silicon absorber on glass were fired with a 532nm Nd:VO laser using a pulse length of 16ns with stepwise increasing intensity. After analysing the influence of the laser intensity on the laser-fired contacts, the effect of different sample topographies corresponding to different grain orientations of the polycrystalline LPC sample, was investigated. The improvement of conductivity within the laser-fired spot was clearly confirmed. The crater diameter was found to increase independently of the grain orientation with increasing laser intensity. Surprisingly, it was found that the rim of the laser-fired spot at the transition to the unmodified silicon material has a much higher conductivity than the spot middle.
Authors : S. Dellis1, N. Kalfagiannis2, Α. Khairi2, P. Patsalas1, D.C. Koutsogeorgis2
Affiliations : 1Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, GR-54124, Greece; 2School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, United Kingdom
Resume : ZnO has a wide bandgap of about 3.4eV at room temperature and its luminescence has received considerable attention. In this study the manipulation of the luminescence of ZnO by laser annealing (LA) and/or by the influence of plasmonic metal nanoparticles in contact with the ZnO film are presented; the metal nanoparticles were produced by laser processes resulting in a wide size distributions ranging from 20 to 300 nm. For the purpose of this study, ZnO thin films were prepared using RF magnetron sputtering from a ZnO target and their microstructure was modified with single pulse LA process that affects their photoluminescence. In particular, the photoluminescence of the sputtered ZnO could be either in the UV, due to the Near-Band Emission (NBE), or in the visible range, due to the Deep-Level Emission (DLE) depending on the different microstructure as a result of different LA conditions. Secondly, the enhanced outcoupling of ZnOs photoluminescence due to existence of plasmonic nanoparticles is also investigated. For this reason, plasmonic nanoparticles exhibiting localized surface plasmon resonance (LSPR) at different spectral positions were fabricated with the combination of RF magnetron sputtering (for ZnO and metal deposition) and LA (for ZnO refinement and metal nanoparticles formation). Different LA conditions were used in order to prepare plasmonic nanoparticles with different LSPR wavelength in order to enhance either the NBE or the DLE of the modified ZnO thin films.
Authors : S. El hamali(a),, W.M. Cranton(a), (b), N. Kalfagiannis(a), X. Hou(c), R. Ranson(a), D.C. Koutsogeorgis(a)
Affiliations : (a) School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK (b) Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK (c) Mechanics, Materials and Structures Research Division, Faculty of Engineering, The University of Nottingham, Nottingham, NG7 2RD, UK
Resume : The potential for nanosecond laser annealing (LA) to significantly enhance the electrical and optical characteristics of Aluminum doped ZnO (AZO) films deposited by RF-magnetron sputtering at low-temperature is demonstrated in our current work. Highly transparent and conductive AZO thin films were fabricated after optimizing both the deposition and the LA parameters. Under optimized deposition parameters, the 180 nm thick AZO thin films showed a resistivity of 1×10-3 Ω.cm, corresponding to a sheet resistance of 56 Ω/□, with carrier mobility 15.3 cm2/Vs, and carrier density 3.84×1020 cm-3. These electrical characteristics were enhanced after LA to a resistivity of 5×10-4 Ω.cm, corresponding to 28 Ω/□, 19.3 cm2/Vs, and 6.21×1020 cm-3 respectively. Moreover, the average visible transparency was enhanced from 85% to 90%. This combination of RF magnetron sputtering and ELA produces reliably AZO thin films with electro-optical characteristics that are very close to those of ITO, but crucially via low temperature and low thermal budget processing. Moreover, the adapted fabrication route could be applied to volume production, as the needed energy density for optimum ELA to half the resistivity is rather low (125 mJ/cm2).
Authors : K. V. Khishchenko,¹ R. S. Belikov,¹ I. K. Krasyuk,² A. Yu. Semenov,² I. A. Stuchebryukhov,² O. N. Rosmej,³ T. Rienecker,³ M. Tomut³
Affiliations : ¹Joint Institute for High Temperatures RAS; ²General Physics Institute RAS, Moscow, Russia; ³GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
Resume : On the laser facilities Kamerton-T and PHELIX, spallation phenomena were studied experimentally in graphite targets with nano- and picosecond shock-wave action. In the range of strain rates from 1/µs to 10/µs, data of dynamic tensile strength of this material were obtained. Spallation was observed not only on the backside of the targets, but also on their front surface. By using optical and scanning electron microscopy, the morphology of the front and back surfaces of the targets is studied. A comparison of the dynamic strength of graphite with the dynamic strength of synthetic diamond is done.
Authors : A.Talbi (1), A.Petit(1), S.Kaya boussougou (1), C. Boulmer-Leborgne (1), G. Gautier (2), T. Defforge (2), N. Semmar(1)
Affiliations : 1) GREMI, UMR 7344 CNRS-Université Orleans, 45067 Orléans Cedex 2, France; 2) GREMAN, UMR 7343 CNRS-Université F. Rabelais de Tours, CNRS, CEA, INSA-CVL, 16 rue P. et M. Curie, 37071 Tours cedex 2, France
Resume : Laser-induced periodic surface structures (LIPSS) were formed on Si (c-Si) and porous Si (p-Si) surfaces irradiated by ultra-short pulsed laser beams at 266 nm central wavelength. Two utlra-short laser beams were used in this study: the first one is a Nd:YAG laser beam with 40 ps time duration and a repetition rate between 1-10 Hz, and the second is a Ti:Sapphire laser beam with a pulse duration close to 100 fs and a repetition rate in the range 1-1000 Hz. As reported in several papers, the shape and the spatial period of the obtained structures are strongly depending on the laser parameters: pulse duration, number of pulses and the beam fluence (dose). In this paper we aim to compare the dynamic of LIPSS formation on silicon substrates achieved at the femto and the pico time scale. Physics of interaction is obviously hugely different in those two regimes. Also, our methodology is to start our application with the c-Si substrate for comparing the LIPSS process formation to the literature. After this first step, we aim to study the p-Si case in order to compare the interference between the LIPSS and the nano-pores obtained in both regimes. We expect to evidence a huge change of the LIPSS structure in the case of the picosecond beam due to the presence of the liquid phase at the first stage (few laser doses) of laser interaction. Physico-chemical analyses (SEM, TEM, AFM and FFT images) are achieved to discuss the results on the LIPSS process formation in the p-Si case function of laser dose.
Authors : T.T.D. Huynh, G. Savriama, N. Semmar
Affiliations : GREMI, UMR 7344 CNRS-Université Orleans, 45067 Orléans Cedex 2, France
Resume : Laser-induced periodic surface structures (LIPSS) were formed on Cu/Si thin films using Nd:YAG laser beam (40 ps, 10 Hz, 30 mJ/cm2 (c-Si). The study of ablation threshold using linear and non-linear accumulation behaviour is leading to proof that LIPSS formation is always achieved over melting when varying the number of pulses from 1 to 10.000. Also, real time reflectivity signals exhibit typical behaviour to stress the formation of a liquid phase during the laser-processing regime. Atomic Force Microscopy (AFM) analyses have shown the topology of the micro-crater containing regular spikes with different amplitude. Those results are discussed with respect to the beam dose but also function of film thicknesses in the range 200 to 1000 nm. Transmission Electron Microscopy (TEM) technique allows finally to determine three distinguished zones in the close region of an isolated protrusion. The central zone is a typical crystalized area of few nanometers surrounded by a mixed poly-crystalline and amorphous area. In the region far from the protrusion zone Cu thin film structure is mainly amorphous. Real time reflectivity, AFM and TEM analyses evidence the formation of a liquid phase during the LIPSS formation in the picosecond regime. A two-temperature model (TTM) is also employed to check the lattice temperature level during the processing in the picosecond regime.
Authors : J. Dutta Majumdar1, , R. Kumari1, Heino Besser2, Tim Scharnweber3, Wilhelm Pfleging2,4
Affiliations : 1Dept. of Metal. & Maters. Eng., I. I. T. Kharagpur, W. B. 721302 2 Karlsruhe Institute of Technology, IAM-AWP, P.O. Box 3640, 76021 Karlsruhe, Germany 3 Karlsruhe Institute of Technology, IBG-1, P.O. Box 3640, 76021 Karlsruhe, Germany 4 Karlsruhe Nano Micro Facility, H.-von-Helmholtz-Pl. 1, 76344 Egg.-Leopoldshafen, Germany
Resume : In the present study, laser surface texturing with line and dimple geometry has been developed using a ArF excimer laser operating at a wavelength of 193 nm with a pulse length of 5 ns. Following surface texturing, an extensive characterization of the textured surface has been carried out by scanning electron microscopy, electron back scattered diffraction (EBSD) technique and X-ray diffraction techniques. There is a significant refinement of microstructure along with a higher mass fraction of -titanium phase and oxides of titanium (rutile, anatase and few Ti2O3 phase) in the textured surface as compared to as-received one. The area fractions of linear texture and dimple texture measured by image analysis software were 45 % and 20 %, respectively. The surface energy (and hence, wettability) was decreased due to linear (29.6 mN/m ) texturing and increased due to dimple ( 67.6 mN/m) texturing as compared to as-received Ti-6Al-4V (37 mN/m ).
Authors : K. Savva(1),(2), G. Kakavelakis(3), M. Sigletou(1),(2), D. Konios(3), M. M. Stylianakis(3), C. Petridis(3), C. Fotakis(1),(2), E. Kymakis(3), E. Stratakis(1),(2)
Affiliations : 1. Foundation for Research & Technology Hellas, Institute of Electronic Structure and Laser (IESL-FORTH), P.O. Box 1527, Heraklion 711 10, Greece 2. University of Crete, Dept. Of Materials Science and Technology, Heraklion 714 09, Greece. 3. Technological Educational Institute (TEI) of Crete, Heraklion, 71003, Greece
Resume : This paper reviews our recent work on the pulsed laser processing of graphene-based materials for organic photovoltaic applications. In particular we report on a rapid and facile method for the simultaneous reduction, doping and functionalization of GO. This technique is compatible with flexible, temperature sensitive substrates and was initially applied for the efficient production of highly transparent and conductive flexible graphene-based electrodes. It is based on the use of femtosecond laser irradiation for the in-situ, non-thermal, reduction of spin coated GO films on flexible substrates over a large area. Furthermore, we present a fast, non-destructive and roll to roll compatible photochemical method for the simultaneous partial reduction and doping of GO nanosheets through ultraviolet laser irradiation in the presence of reactive Cl2 precursor molecules . By tuning the laser exposure time, it is possible to control the doping and reduction levels and therefore to tailor the work function (WF) of the GO-Cl derivatives from 4.9 eV to a maximum value of 5.23 eV, a WF value that matches the HOMO level of most polymer donors employed in OPV devices . Moreover, we demonstrate the pulse UV laser - assisted photochemical functionalization of GO with small molecules as an efficient technique to realize polymer electron acceptors . Potential applications of pulsed laser synthesized and modified materials in electronics, particular to bulk heterojunction organic solar cells are demonstrated and discussed. References 1 K. Savva, Y.H. Lin, C. Petridis, E. Kymakis, T.D. Anthopoulos, E. Stratakis, Journal of Materials Chemistry C, 2, 5931-5937 (2014).  M. M Stylianakis., M. Sygletou, K. Savva, G. Kakavelakis, E. Kymakis, E. Stratakis, Photochemical Synthesis of Solution-Processable Graphene Derivatives, Advanced Optical Materials , DOI: 10.1002/adom.201400450 (2015). 3 E. Stratakis, K. Savva, D. Konios, C. Petridis, E. Kymakis, Nanoscale, 6, 6925-6931(2014).
Authors : J. Tomko, R. Jimenez, D.M. Bubb, and S.M. OMalley
Affiliations : Department of Physics, Rutgers University, Camden, NJ 08102, USA
Resume : Over the past decade, Laser Ablation in Liquids (LAL) has become a popular method for the synthesis of colloidal nanoparticles. While the process is simple in execution, variation in particle size and polydispersity between product batches has been a problematic aspect of the method, even when great care in terms of experimental consistency is taken. In this regard, we investigated a relatively overlooked aspect that could be responsible for such variations in nanoparticle morphology. This aspect being the relative orientation between the laser polarization and linear features on the target surface that result from polishing. This effect was studied via shadowgraphy imaging of the induced cavitation bubble as a means of inferring the relative absorption of the incident pulse. The influence on particle size will also be presented. These results will be discussed in terms of reflectivity of the surface features, effective penetration depth, and thermal confinement within the ridges.
Authors : Sergey V Arkhipov(1), Moritz Grehn(2), Nils Griga(2), Hans J. Eichler(2), Igor K Meshkovskiy(1), Vladimir E Strigalev(1), Sergey V Varzhel(1), Anna S. Mun'ko(1), Andrey V. Kulikov(1)
Affiliations : (1) ITMO University, Kronverkskiy pr. 49, 197101 St. Petersburg, Russian Federation (2) Technical University Berlin, Institute of Optics und Atomic Physics, Str. des 17. Juni 135, 10623 Berlin, Germany
Resume : Fiber Bragg gratings (FBG) written in birefringent optical fibers can be used as advanced sensors for biomedical or mechanical applications. Here, FBG writing in an unique birefringent optical fiber by a single 20 ns KrF excimer laser (248 nm) pulse with a phase mask method and Point-by-point inscription by Ti:Sa femtosecond laser (800 nm) is demonstrated. This birefringent optical fiber has an elliptical stress cladding, in which a fiber core of high GeO2 doping is embedded in, and which has an additional isolating circular cladding. To enhance the photosensitivity of the fiber the concentration of GeO2 in its core was increased to 16 mol. A second method for the production of FBGs, the Point-by-point inscription of the refractive index changes has advantages over the conventional phase mask method. Due to the nonlinear interaction mechanism of the ultrashort laser pulses with the dielectric material, the grating structures can be created without stripping off the acrylate coating. This method allows to inscribe diffractive structures with or without codoping of GeO2 in the fiber core. FBGs with the reflectivity up to 10% have been written through the acrylate coating into the fiber core with 4 mol. % GeO2. Obtained FBGs can be used for new generations of measurement systems, such as fiber-optic hydrophone or monitoring system of extent objects (pipelines, railways, borders).
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Authors : F. Dumitrache1, 2, R. Alexandrescu1, I. Morjan1, C. Fleaca1, 2, G. Huminic3, L. Vekas4, E. Vasile5
Affiliations : 1 National Institute for Lasers, Plasma and Radiation Physics (NILPRP), Laser Photochemistry Laboratory, 409 Atomistilor Street, 077125, Magurele Bucharest, Romania 2 "Politehnica" University of Bucharest, Physics Department, Independentei 313, Bucharest, Romania 3 "Trasilvania" University, 29 Eroilor Blv., 500036, Brasov, Romania 4 Acad Romana, Timisoara Branch, RO-300223 Timisoara, Romania 5 "Politehnica" University of Bucharest,, Faculty of Applied Chemistry and Material Science, Dept. of Oxide Materials and Nanomaterials, 1-7, Gh. Polizu Street, 011061 Bucharest, Romania
Resume : Iron carbides core with carbon shell nanoparticles have gained interest for biomedical applications, magnetic separations and as heat transfer agent. These nanoparticles with core/shell structure: Fe(C)@C were synthesized in a single step approach using the laser pyrolysis method. In order to diminish the carbon shell thickness, the iron pentacarbonyl vapors (Fe precursor) were mixed with an ethylene flow - diluted with Ar or H2 - used as carbon donor source. Elemental analysis performed by EDX reveals that the nature and proportion of diluted gas has an important effect on the as synthesized nanoparticles especially for their iron and oxygen content. Using optimized conditions, nanopowders with ~ 40 at.% Fe and less than 8 at. % O were synthesized. The morphology of such samples were investigated by TEM analysis and the particles has around 12 nm mean diameter and carbon shells with 3-4 onion-like graphene layers. The at XRD and SAED analysis of nanopowder samples with a protective carbon shell reveal only the presences of iron carbides (Fe7C3 or Fe3C) or αFe crystalline phases, whereas the Raman analysis showed the amorphous carbon peaks and the lack of iron oxides phases. Magnetic measurements performed at room temperature revealed values for the saturation magnetization up to 110 emu/g in a strong dependence with the iron proportion in nanopowders. Also, an in-situ surface functionalization was performed by supplementary introduction of acrylic acid vapors in the reactive precursors. The FT-IR analysis for these nanopowders show the presence of functional groups from acrylic acid derivatives. Such functionalized powders were easily dispersed in aqueous solutions when the CMCNa were used as stabilizer.
Authors : M. Boutinguiza1, R. Comesaña2, F. Lusquiños1, A. Riveiro1, J. del Val1, J. Pou1
Affiliations : 1 Applied Physics Department, University of Vigo EEI, Lagoas-Marcosende, 9. Vigo, 36310, SPAIN 2 Materials Engineering, Applied Mechanics and Construction Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo, 36310, SPAIN
Resume : Nanoparticles and films of noble metals currently have attained wide popularity and aroused intense research interest in nanotechnology due to their well known properties, such as good conductivity, localized surface plasmon resonances, antibacterial and catalytic effects, etc. They are used in many different areas, such as medicine, solar cells, scientific investigation, etc. In this work we report a method consisting of a combination of laser ablation in liquids and electrophoretic deposition to produce Ag nanoparticles and deposit them at the same time on a substrate used as electrode. The obtained particles and films were characterized by means of transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and UV/VIS absorption spectroscopy. The coatings composed of Ag nanoparticles ranging from few to 60 nm were uniform and showed a clear localized surface Plasmon resonance.
Near-field-assisted laser processing : P. Delaporte
Authors : Mitsuhiro Terakawa
Affiliations : Department of Electronics and Electrical Engineering, Keio University
Resume : An enhanced optical field generated around a nanostructure can concentrate optical energy into nanoscale space as a nanolens. Thanks to the nonthermal and intense processing by ultrashort pulsed laser, a merged method of the enhanced optical field and femtosecond laser processing enables high-precision processing on various kinds of materials. In this presentation, femtosecond laser processing with the enhanced optical field toward biomedical applications will be described. In our study, both the material in the vicinity of nano-structure and nano-structure itself can be a target of laser ablation. As for the former case, the focused optical field under polymer microspheres, which were conjugated to cell membrane, provides simultaneous cell membrane perforation of multiple cells by a single shot of 800 nm femtosecond laser illumination, enabling the introduction of exogenous molecules into cells. Owing to a little linear optical absorption and relatively low scattering coefficients at near-infrared wavelength, the interaction zone is localized in a focused spot on the cell membrane by nonlinear interaction, resulted in a little damage to the cell. As for the latter case, an enhanced optical field generated on a shell of hollow microcapsules contributes to localized disruption of the shell without doping with metals or dyes. This method has potential to realize light-triggered release of drug molecules embedded in the microcapsule. In the presentation, theoretical and experimental study on laser processing with enhanced-ultrafast optical field will be presented followed by recent works for biomedical applications.
Authors : Sylvain Lecler, Andri Abdurrochman, Julien Zelgowski, Frédéric Mermet, Bernard Tumbelaka, Joël Fontaine
Affiliations : ICube, Université de Strasbourg, INSA; IREPA Laser, Strasbourg Universitas Padjadjaran, Bandung
Resume : A Photonic jet is known as a high concentrated low diverging beam which can be generated in the shadow side of a micrometric dielectric particle (sphere or cylinder). Its full-width at half maximum can be smaller than a half wavelength, beyond the diffraction limit. Thus, the incident power density of a laser source can be concentrated more than 200 times by a dielectric particle. It is a non-resonant phenomenon which takes place in the near-field of dielectric spheres even it concerns a propagative wave. A lot of possible applications have been imagined. However the 3D manipulation of microspheres is not obvious to control a potential photonic jet with matter interaction. Hence, be able to obtain photonic jet out of an optical fiber is a major issue. Namely if the same photonic jet can be achieved at the tip of an optical fiber, its control for material processing will be easier. Our study shows how to obtain photonic jet out of classical filled core optical fiber. The parameters dependences between optical fiber tip and photonic jet properties are more complexes and will be theoretically exposed. Methods to achieve such a needed optical fiber tip will be described. The ability to generate photonic jet out of the shaped optical fiber will be experimentally demonstrated and the potential applications for material processing exposed.
Thin film laser processing : S. Orlando
Authors : R. J. Peláez1, C.N. Afonso1, M. kereň2, J. Bulíř3
Affiliations : 1 Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid, Spain;2 Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague Brehova 7, 115 19 Prague 1, Czech Republic;3 Institute of Physics, ASCR, v.v.i., Na Slovance 2, Prague, Czech Republic
Resume : Laser interference is a versatile technique for producing patterned surfaces, the latter being very attractive due to their unique optical, electrical and chemical properties. When applied to metal films, the metal dewets from the substrate in the areas exposed to intensity maxima where formation of nanoparticles (NPs) and/or metal transport is generally reported. This work aims to show that the initial film nanostructure plays an essential role on the features of the patterns. We have produced silver layers with an effective thickness around 9 nm and having a quite different initial nanostructure, i.e. continuous or discontinuous film. Patterns with periods in the microscale have been produced by exposing a phase mask to a single pulse of an excimer laser operating at 193 nm. They are formed by regions of almost untrasformed film and regions where the film breaks up into isolated NPs due to laser induced melting. For the case of discontinuous sample, the temperature distribution across the pattern matches almost perfectly the intensity profile and thus the interface between the two regions of the pattern is sharp. For the case of continuous samples, the temperature distribution becomes smoothed due to lateral heat transfer and several different levels of transformation can be eventually found across the pattern. The mechanisms leading to these different levels are finally discussed as well as the importance of the pattern period.
Authors : Girolamo Mincuzzi, Luigi Vesce, Malte Schulz-Ruthenberg, Elmar Gehlen, Andrea Reale, Aldo Di Carlo, Thomas M. Brown
Affiliations : CHOSE (Centre for Hybrid and Organic Solar Energy), Department of Electronic Engineering, University of Rome - Tor Vergata, via del Politecnico 1, Rome, 00133- Italy; Fraunhofer Institute for Laser Techonology , Steinbachstrasse 15, Aachen, 52074 Germany
Resume : We present innovative approaches for the fabrication of Dye Solar Cells (DSC) on glass substrates by processing all the main constituent materials with laser radiation, eliminating thus all the conventional thermal processes. We show that lasers can be successfully implemented for 1) patterning of the metal-oxide TiO2 film via ablation, 2) laser-assisted platinization of the counterelectrode, 3) encapsulation via laser-sealing of thermoplastic gaskets, and also 4) laser-sintering of the nanocrystalline TiO2 film. All the mentioned processes are optimized and utilised for the fabrication of the first efficient and durable all-laser-manufactured glass DSC. The power conversion efficiency of a fully laser-fabricated device was 5.3%, a value just over that of a cell fabricated with the same materials-set but processed with conventional procedures (5.2%). We also developed laser and lower power-density but broader UV-lamp sintering procedures for the TiO2 on thin flexible substrates delivering over 4% efficiency when incorporated in DSCs with transparent plastic counterlectrodes. These results pave the way for new scenario of an entire, laser-based, manufacturing line customized for dye solar cell technology with benefits related to its effective processing, automation, large area scalability and even embodied energy.
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Plasma processing of advanced materials : B. Mitu
Authors : T. Labbaye, M. Gaillard, E. Kovacevic, Ch. Boulmer-Leborgne, J. Simmoneau, T.Lecas, M. R. Ammar,* A. Canizarès,* N. Raimboux*, G. Guimbretière*, P. Simon*
Affiliations : GREMI Université d'Orléans-CNRS, 14 rue d'Issoudun, 45067 Orléans cedex2 FRANCE *CEMHTI CNRS Avenue de la recherche scientifique 45001 Orléans FRANCE
Resume : Advanced carbon coatings can be used for example as gas sensors, catalysts or for new design concepts for microfluidic elements or lab on chip applications. In this work, carbon nanotube carpets (CNT) are produced by PECVD technique (C2H4 - H2. RF plasma) assisted by a transition metal catalyst on many different substrates (metal, silicon, nitride/silicon). As a base for CNT growth, thin films of metal catalysts are deposited by PLD. To obtain nanoparticles, these thin films are subsequently heated to temperatures between 550 700 C° and treated in hydrogen plasma (within the same vacuum system). The CNT carpet structure (length, width, and diameter distribution) mainly depends on a variety of experimental parameters such as catalyst nanoparticle size and density, growth temperature, and various other conditions. The characterization of the various experimental parameters involved in the resulting quality of CNT is determined by different ex situ techniques as SEM, TEM, NEXAFS, XPS. In addition a portable and highly sensitive Raman setup was successfully coupled with the PECVD reactor enabling in situ growth monitoring of multi-wall carbon nanotubes despite plasma conditions. This new analysis tool can be interesting to monitor the growth under various experimental conditions and define easily the available range to obtain the best results.
Authors : Hanearl Jung, Clement Lansalot-Matras, Hyungjun Kim
Affiliations : School of Electrical and Electronic Engineering Yonsei University; Air Liquide Korea Co.; School of Electrical and Electronic Engineering Yonsei University
Resume : High-k materials such HfO2 and ZrO2 have been extensively studied as alternative gate dielectrics of SiO2 due to its large direct tunneling currents when it is very thin. In in thin film transistors (TFTs), HfO2 and ZrO2 show more desirable properties than SiO2; low driving gate voltage of TFT, increased physical thickness to prevent electron tunneling with high capacitance value. To deposit high-k materials, plasma-enhanced atomic layer deposition (PE-ALD) is widely used but its low growth rate precludes its use for relatively thick structures. However, several papers about pulsed plasma-enhanced chemical vapor deposition (P-PE-CVD) were introduced as an alternative approach for ALD. They demonstrated self-limiting growth of Al2O3 and Ta2O5 with higher growth rate than PE-ALD. But fundamental studies for electrical properties of the P-PE-CVD films by fabricating TFTs and observation of device stability are rarely reported. In this paper, we observed self-limiting growth of HfO2 and ZrO2 using newly developed precursors ((C5H5)M[N(CH3)2]3, M = Hf, Zr) and O2 plasma with P-PE-CVD and PE-ALD. We compared electrical properties of films by fabricating MOSCAPs and IGZO TFTs. All films showed good dielectric properties (k value about 20~22 for HfO2 and 22~25 for ZrO2 with low leakage current<1x10^-8 A/cm^2) and excellent performance of TFTs (Ion/Ioff>10^8, μ>9 cm^2/Vs) with superior device stability in stability test (ΔVth<-0.5V after 3 hours of gate bias stress; VG=-20V).
Authors : F. Arias-González (a), J. del Val (a), R. Comesaña (b), J. Penide (a), F. Lusquiños (a), F. Quintero (a), A. Riveiro (a), M. Boutinguiza (a), J. Pou (a)
Affiliations : (a) Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo, E- 36310, Spain.; (b) Materials Engineering, Applied Mechanics and Construction Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo, E- 36310, Spain.
Resume : Laser cladding is a method to deposit a coating on a substrate using laser as heating source. The interaction of the laser beam with the substrate generates a molten pool, in which the precursor material is fed. The relative movement between the beam and the workpiece makes possible to generate a layer with a thickness ranged from microns to millimeters. This technique can be applied to improve the surface properties of a new part and also in the restoration of worn or damaged components. Cast iron is a relatively inexpensive material, which presents a good castability, machinability and resistance, but it can be weakened by the oxidation. The surface properties of cast iron can be enhanced by a Ni-base alloy coating, a material with excellent performance under conditions of abrasion or corrosion at elevated temperatures. In this research work, a fiber laser is used to generate a NiCrBSi coating over flat substrates of gray cast iron (EN-GJL-250) and nodular cast iron (EN-GJS-400-15). The relationship between processing parameters (laser power and scanning speed) and geometry of a single laser track is examined. Microstructure and composition were studied by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD). The hardness and elastic modulus were analyzed by means of micro- and nanoindentation.
Authors : Vorobets H.I., Strebezhev V.V., Fochuk P.M., Halavka Yu.B., Vorobets O.I., Strebezhev V.M., Balazuc V.N.
Affiliations : Yuriy Fedkovych Chernivtsi National University
Resume : Photosensitive elements based on layered semiconductor group A3B6 - In4Te3 and In4Se3 were obtained by liquid phase epitaxy and by vacuum sputtering Al, Ag, Au for obtaining of the metal thin films on the surface of single crystals for these compounds. To obtain epitaxial layers In4Te3 and In4Se3 was used method of isothermal liquid phase epitaxy with option of passing an electric current through the boundary melt-substrate. Density DC changed within 0,8- 2,5 A / cm2, while simultaneously take into account the effect on the crystallization layers of thermoelectric Peltier effect, thermal conductivity processes, diffusion and of charge transfer. Optimization of structural-phase state epitaxial layers In4Te3 and In4Se3 after LPE process was performed by laser annealing using YAG-laser (λ = 1,06 m, τ ~ 1 ÷ 4 ms) with a density of radiation I0 ~ 20 ÷ 30 kW / cm2. Perfection structure of epitaxial layers and homogeneity of phase composition was studied by methods SEM, AFM and of the X-ray electron probe microanalysis. Effect of laser radiation on optical and electrical characteristics of heterostructures In4Te3 - In4Se3 and structures with a Schottky barrier, such as (Al, Ag, Au) - In4(Se3)1-хТe3х studied by changing their spectral photosensitivity and IV and CV characteristics. The methods of SEM and AFM-microscopy were established optimum conditions for laser annealing in which improved epitaxial layer structure heteroboundary In4Te3 - lining, and which reduces the impact of recombination processes in this field. In the study in the AFM cross-layers found in nanostructured elements heteroboundary, that can exert influence on the processes of photosensitivity. Investigation C-V - characteristics of barrier structures Au - crystal In4(Se3)1-хТe3х showed that the nature of the curves corresponds to the presence of narrow-band as well as wide-band phases in the structure of the film after the PLI. Determined from the slope of the curves activation energy E0 given the chemical potential values for the above carrier concentrations are in good agreement with the values of the band gap of the possible phase compositions component.
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