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Characterization of advanced materials


Pulsed-laser deposition of thin films : 30 years of fundamentals, innovative materials and applications

Introduction and scope:

Since the discovery of high-temperature superconductors 30 years ago, pulsed-laser deposition (PLD) has emerged as a very popular technique for depositing a wide range of materials ranging from metals, semiconductors, dielectrics, organics and biomaterials. Today, PLD is applied by a broad range of research groups in the world to grow thin and thick films from single atomic layers to nearly single crystalline epitaxial layers, heterostructures or nanostructured films.

The aim of the symposium "Pulsed-laser deposition of thin films: 30 years of fundamentals, innovative materials and applications" is first to bring a comprehensive and if possible an exhaustive review of the fields covering a broad range of topics in PLD of thin films : fundamental and practical aspects of the technique, physics of laser-material interactions, laser-plume dynamics and related diagnostics, film or nanoparticles formation. Second, a large part of the program will be devoted to topics dealing with functional films and heterostructures in the areas of photonics, electronics, sensing, biology, tribology, energy production and storage. The Symposium will present the latest achievements exploiting the new capabilities of current laser sources (ultrashort pulses, high repetition rate) and of specific equipments, the enhancement effects that arise in the properties of thin films and consequently the capability to produce device and systems with PLD. Due to the inherent interdisciplinary character of PLD, and to the broad range of covered topics, it is expected that the Symposium will facilitate the discussion and exchanges between laser and material scientists and researchers working in nanoscience and nanotechnology. Regarding simply at the European level, the number of research groups using PLD is larger than 30 who are very active in this field, corresponding to a multidisciplinary community, (chemistry, physic, electronic …labs), which will make such a symposium attractive for around 80-100 attendees coming from Europe and elsewhere.

Hot topics to be covered by the symposium:

  • Fundamentals and modeling of PLD.
  • Plasma dynamics and diagnostics during PLD
  • Deposition of thin films and coatings of functional materials for display technologies, devices and heterostructures in
  • solar cells, spintronics, multiferroics, magnetism, optoelectronics, thermoelectrics, piezoelectrics, electrochemistry…
  • PLD of organics, polymers and biomaterials (MAPLE).
  • PLD of non oxide materials : DLC, nitrides, CNT, quasicrystals, hard coatings
  • PLD-based specific techniques: cross-beam, double beam, off axis deposition, combinatorial
  • Laser generation of nanoparticles and nanocomposite films
  • 2D/3D micro-nanofabrication with PLD
  • New laser sources (high repetition rate, short pulses…) for PLD.
  • Industrial trends : large-area PLD, devices and microsystems

Tentative list of invited speakers:

  • Salvatore Amoruso, University of Napoli, Italy
  • Corinne Champeaux, Université of Limoges, France
  • Douglas Chrisey, Tulane University, USA
  • Maria Dinescu, NILPRP, Bucharest
  • Judith Driscoll, University of Cambridge, UK
  • Robert Eason, University of Southampton, UK
  • Michael Lorenz, University of Leipzig, Germany
  • Guus Rijnders, University of Twente, The Netherlands
  • Matjaz Spreizer, Institute Jozef Sefan, Ljubljana, Slovenia
  • Rosalia Serna, CSIC, Madrid, Spain
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(His)tory and fundamentals : Maryline GUILLOUX-VIRY
Authors : Douglas B. Chrisey
Affiliations : Department of Physics and Engineering Physics Tulane University

Resume : The use of lasers to deposit thin films occurred shortly after the discovery of lasers. The technique which has come to be known as Pulsed Laser Deposition, or PLD, did not really become popular or commonplace until 25 years later with the discovery of high temperature superconductors (HTS). It was the great promise of the applications of HTS in electronics that catalyzed the development of a novel physical vaporization technique that we know today as PLD. Both conceptually and experimentally, PLD is an extremely simple technique and yet it provided the high quality and reproducibility that was necessary to realize the extreme HTS thin film properties and novel applications. Subsequently, PLD was successfully applied to many other ceramic oxides including ferroelectrics, ferrites, transparent conducting oxides just to name a few. Today, PLD has become the preeminent technique to deposit ceramic oxide thin films, but the attributes which make PLD so special came from significant technical advances from numerous researchers. This presentation will be a personal account of the difficulties encountered in the early stages of the development of PLD.

Authors : Felix V. E. Hensling 1, Chencheng Xu 1, Felix Gunkel 2, Regina Dittmann 1
Affiliations : 1 Peter Grünberg Institut 7, Forschungszentrum Jülich GmbH, Jülich, Germany; 2 RWTH Aachen University, Institute of Electronic Materials (IWE 2), 52056 Aachen

Resume : The oxygen pressure applied during the pulsed laser deposition of metal oxides plays a key role for the properties of the resulting thin films. For the deposition of fully oxygenated thin films, a high oxygen pressure is necessary to either compensate or prohibit the oxygen ejection from the thin film induced by the high energetic species of the plasma plume. At the same time some oxides require a low deposition pressure in order to adjust a low valence state of the involved cations, or to obtain layer-by-layer growth, as high growth pressures result in 3D growth (e.g. LaAlO3). SrTiO3 (STO) is an example for a widely used substrate with a high oxygen pressure sensibility. When comparing the existing literature regarding the reduction of SrTiO3 during thermal treatments it is conspicuous that one finds different oxygen pressures required to achieve reduction, namely, physical pressures of ~ 10-6 mbar for vacuum annealing and oxygen partial pressures of ~ 10-17 mbar for chemically controlled reducing atmospheres (e.g. H2/H2O/Ar gas mixtures). In this work, we will unravel this contradiction by examining the impact of 1) residual gases present during vacuum annealing in our pulsed laser deposition chamber and 2) attached measurement devices, namely a cold cathode gauge and a mass spectrometer, on the reduction behavior of SrTiO3. For mere thermal annealing, our results prove the attached measurement devices to be primarily responsible for the reduction of SrTiO3 in the PLD chamber by shifting the thermodynamic equilibrium to a more reducing atmosphere. In addition, we investigated the impact of our findings on the PLD growth at low pressure. We find that during deposition the reduction triggered by the presence of the laser plume dominates the reduction process and the impact of the measurement devices plays a minor role.

Authors : D. Craciun1, O. Fufa1, G. Socol1, D. Cristea2, D. Pantelica3, P. Ionescu3, R. Trusca4, E. Lambers5, and V. Craciun1
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Măgurele, Romania 2Materials Science Department, Transilvania University, Brasov, Romania 3Horia Hulubei National Institute for Physics and Nuclear Engineering, Magurele, Romania 4Polytechnic University of Bucharest, Bucharest, Romania. 5MAIC, University of Florida, Gainesville, USA

Resume : The pulsed laser deposition (PLD) is probably the best technique to grow thin films to investigate the interdependence between structure, composition and properties. The control of the deposition conditions (substrate temperature, nature and pressure of the gaseous atmosphere, laser fluence, repetition rate, laser wavelength and deposition geometry) will results in the growth from a single target of films having different stoichiometry, crystalline grain sizes, texture, stress levels and properties. However, it has been known for many years that the non-uniform thickness profile of the PLD grown films could be accompanied by non-uniform compositions as well, which could result in non-uniform properties. We investigated the dependence of these lateral variations on the mass of the ablated atoms, laser fluence target-substrate distance and nature and pressure of the gaseous atmosphere. X-ray diffraction, X-ray reflectivity, X-ray diffuse scattering, nanoindentation, X-ray photoelectron spectroscopy, scanning electron microscopy and Rutherford backscattering spectrometry techniques were used to observe changes in the structure, chemical composition and properties of PLD grown thin films. Several transition metal nitrides and carbides such as ZrC, TiC, ZrN, TiN as well as indium zinc oxide films were investigated as typical examples of compounds containing atoms with very different atomic masses.

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Thin films and heterostructures of functional materials I : Maria DINESCU
Authors : Robert W Eason, David P Shepherd, Jacob I Mackenzie, Ping Hua, James A Grant-Jacob, Stephen J Beecher, Amol Choudhary, Christos Grivas, Andrew A Anderson, Timothy C May-Smith, Stephen J Barrington, Kate A Sloyan.
Affiliations : Optoelectronics Research Centre, University of Southampton, Southampton, SO171BJ, UK

Resume : We have been using PLD to grow doped crystalline films of a range of laser hosts that include garnets (YAG, GGG and other variants), sapphire and, most recently, cubic sesquioxides (Y2O3, Sc2O3, and Lu2O3) for application as optically-pumped waveguide lasers. For the sesquioxides in particular, PLD offers a real advantage in terms of the ~1100K temperature required to grow crystalline thin films in comparison to ~2750K required to grow bulk crystals. We have grown these materials at deposition rates of up to ~5 µm per hour, on cheap and readily available single crystal substrates, which allows rapid production of waveguide samples of the ~10-30 µm thickness required for efficient pumping via high power diode lasers. We will describe the range of PLD techniques we have used to date, that include single-beam, multi-beam, consecutive and combinatorial as well as fast shuttering of multiple laser sources onto different targets. We will discuss strategies we have adopted to grow complex structures in both the vertical and horizontal planes of the waveguides, including multilayers, capped, graded and volume Bragg structures. Finally we will describe post-processing we have performed on the waveguides to improve the final mode quality of the lasing output produced, and to generate q-switched output via local deposition of graphene that acts as a Q-switch. Our current levels of lasing output are approaching 20W in c.w. mode, and we will describe our strategy to exceed this via a MOPA structure using multiple PLD-grown waveguides.

Authors : R Morea1, T.T. Fernadez1,2, J Fernandez3,4, R Balda3,4, J Gonzalo1
Affiliations : 1Laser Processing Group, Instituto de Optica, CSIC, Madrid, Spain; 2Dept. of Physics, Politecnico de Milano, Milano, Italy; 3Dept. of Applied Physics I, Universidad del Pais Vasco UPV/EHU, Bilbao, Spain; 4Materials Physics Center CSIC-UPV/EHU & Donostia International Physics Center, San Sebastian, Spain

Resume : Rare earth doped materials play an important role in the development of all-optical networks. In particular, Er-doped waveguide amplifiers (EDWAs) based on the 4I13/2→4I15/2 emission transition of Er3+ at 1.5 µm can enhance light signals on robust, low-cost, miniature chips. However, the glass hosting Er ions determines their photoluminescence response. In this regard, fluorotellurite glasses present clear advantages over other glasses, such as: a wide transmission region, high refractive index, good glass stability, high corrosion resistance and finally, they show high RE solubility and moderate phonon energy. In this work Er-doped TeO2-ZnO-ZnF2 film glasses are synthesized by Pulsed Laser Deposition, since they are promising to develop broadband EDWAs. Their structure is similar to that of the parent bulk glass and they present a very high transparency in the VIS-NIR wavelength range. However, their emission at 1.5 µm was poor. Thus, as-grown films underwent annealing cycles to improve their NIR emission but, at the same time, avoiding structural and optical modifications. In such a way, the optimal annealing cycle was determined. It led to a 20-fold increase of the emission intensity without affecting the glass film composition and structure. Therefore, the film transparency and refractive index did not vary upon annealing. The annealing significantly decreased the OH- content of the film glasses, which has a strong impact on the improvement of their NIR emission.

Authors : Michael Lorenz, Vera Lazenka.
Affiliations : Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, D-04103 Leipzig, Germany; Katholieke Universiteit Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200 D, 3001 Leuven, Belgium.

Resume : Multiferroic and magnetoelectric materials are highly interesting because they show novel functionalities in terms of simultaneous ferroelectric and ferromagnetic response, and coupling of both effects. Although magnetoelectric coupling of magnetic and electrical properties was already considered more than 50 years ago, recent progress in materials science and technology and the hope for realization of novel device functionalities has renewed research interest in this area [1]. In particular, complex oxide heterostructures may offer the possibility to realize next generation electronics, such as novel data storage devices [1]. Magnetoelectric composites consisting of several closely coupled phases show advantages compared to single-phase magnetoelectrics in terms of value of magnetoelectric coupling coefficient, control of its temperature dependence, and design of tailored materials for applications. We demonstrate the current status of epitaxial BaTiO3-BiFeO3 superlattices and homogeneous composite thin films grown by pulsed laser deposition. In particular, we show here how to correlate the magnetoelectric voltage coefficient with microstructural features and the magnetic spin structure [2-5]. Up to now, the highest magnetoelectric voltage coefficient of 49 V/cm Oe at 300 K and 1 kHz has been reached in a multiferroic (BaTiO3-BiFeO3)×15 superlattice with total thickness of 208 nm, which is correlated to atomically coherent interfaces [4]. [1] C. A. F. Vaz et al., Adv. Mater. 22, 2900-2918 (2010). [2] M. Lorenz et al., Appl. Phys. Lett. 106, 012905 (2015). [3] V. Lazenka et al., Appl. Phys. Lett. 106, 082904 (2015). [4] M. Lorenz et al., Adv. Mater. Interfaces, 1500822 (2016). [5] M. Lorenz et al., Materials 9, 44 (2016).

Authors : E. Popova [a], J. Lion [a], E. Chikoidze [a], F. Jomard [a], J. Vigneron [b], A. Etcheberry [b], N. Keller [a], and Y. Dumont [a]
Affiliations : [a] GEMaC (Groupe d'Etudes de la Matière Condensée), Université de Versailles Saint-Quentin en Y. & CNRS, Université Paris-Saclay, Versailles, France ; [b] Institut Lavoisier de Versailles (ILV), Université de Versailles Saint-Quentin en Y. & CNRS, Université Paris-Saclay, Versailles, France ;

Resume : Development of materials that show both magnetic and semiconducting properties is crucial for the realization of semiconductor-based spintronic devices. The solid solutions between ilmenite (FeTiO3) and hematite (α-Fe2O3) have recently attracted considerable attention due to their interesting magnetic and electronic properties that are strongly dependent on ordering of cations as well as composition [1-3]. Ferrimagnetic semiconductors arise when the arrangement of cations is ordered, whereas weak frustrated disordered magnetism is observed for disordered cation distribution. The Curie temperatures of ordered phases are higher than room temperature for compositions between 50 mol.% and about 80 mol. % of FeTiO3. DFT calculations have predicted a charge transfer at Fe2O3 and FeTiO3 interfaces in superlattices [6], generated interface magnetism with “giant exchange-bias” [7]. Such effects have been observed natural metamorphic mineral of nanocrystals. By Pulsed Laser Deposition, artificial modulated composition hetero-structures (Fe2-xTixO3-d/FeTiO3)n have been epitaxially deposited on α-Al2O3(0001) substrate, varying the period thickness and the number of periods. Chemical composition has been measured by SIMS and XPS profiles. Magnetic loops exhibit exchange bias signature of this interface coupling and stronger coercive field that single materials thin films. Measured Curie temperature of magnetization is 325K. Transport properties of these artificial superlattices have been investigated. [1] H. Hojo, K. Fujita, K. Tanaka, et al., Appl. Phys. Lett. 89, 082509 (2006); ibidem 89, 142503 (2006) [2] Hamie A., Popova E., Dumont Y., et al. Appl. Phys. Lett. 98, 232501 (2011) [3] Bocher L., Popova E., Nolan M., et al. Phys. Rev. Lett. 111, 167202 (2013) [4] R. Pentcheva and H. Sadat Nabi, Phys. Rev. B 77, 172405 (2008); H. Sadat Nabi, R. J. Harrison, and R. Pentcheva, Phys. Rev. B 81, 214432 (2010) [5] S. A. McEnroe, B. Carter-Stiglitz, R. H. Harrison, et al., Nature Nanotechnol. 2, 631 (2007)

Authors : S. Mesoraca, B. Prasad, M. G. Blamire
Affiliations : Department of Materials Science, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom; Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569 Stuttgart, Germany; Department of Materials Science, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom

Resume : Spin-filtering (SF) across an ultra-thin ferromagnetic insulating barrier between two non-magnetic electrodes can generate highly spin-polarized currents due to the preferential tunneling of one of the two spin orientations. The ferromagnetic insulating spinel ferrites (CoFe2O4, NiFe2O4, MnFe2O4) are the candidates for achieving SF at room temperature as their Curie temperatures are well above 300K. However, high efficiency SF at technologically useful temperatures has been hampered by low structural quality of the barrier due to the lack of non-magnetic electrodes with the same crystal structure and lattice parameter of these complex oxides. We report for the first time the successful growth of spinel metallic-superconducting LiTi2O4 and ferromagnetic insulating CoFe2O4 bilayers on spinel substrates (MgAl2O4). This LiTi2O4(200nm)/CoFe2O4(5nm) system could pave the road to the fabrication of a SF tunnel barrier in a closely lattice-matched all-spinel heterostructure, attempting to largely eliminate defects within the barrier and so greatly enhance the room temperature SF efficiency.

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Plasma dynamics and diagnostics : Corinne CHAMPEAUX
Authors : Salvatore Amoruso
Affiliations : 1) Dipartimento di Fisica "Ettore Pancini", Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli, Italy. 2) CNR-SPIN UOS Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli, Italy.

Resume : Pulsed laser deposition (PLD) has become a widespread approach to the fabrication of thin film of a variety of materials, starting from the high temperature superconductors 30 years ago to the recent oxide perovskite hetero-structures. As the laser technology has advanced, PLD has kept the pace and nowadays also femtosecond laser ablation and deposition has emerged as an interesting technique for the elaboration of nanoparticles and nanoparticles-assembled films. A clear understanding of the PLD process cannot be complete without a deep knowledge of the properties of the laser ablation plasma plume and of the effects that the various parameters have on its properties, thus making PLD an extremely versatile method of material fabrication. In this communication, an overview on the main features of laser ablation plumes generated by nanosecond and femtosecond pulses will be given, addressing the role on many phenomena involved in the propagation dynamics of the ablated species from the target to the substrate. Among the noteworthy examples of PLD physics that will be discussed, the two following are anticipated: i) the striking influence of process parameters (e.g. background gas pressure and substrate temperature) on both the expansion dynamics and the deposition rate in nanosecond PLD of oxides; ii) the peculiarities of the femtosecond laser ablation plasma plumes involving fast ions and nanoparticles generation.

Authors : R.Groenen, K. Orsel, H.M.J. Bastiaens, K.J. Boller, A.J.H.M. Rijnders, G. Koster
Affiliations : Inorganic Materials Science, MESA+ Institute for Nanotechnology, University of Twente, The Netherlands

Resume : Pulsed Laser Deposition (PLD) has been established in recent years as a versatile thin film deposition technique for complex materials, including complex oxides. The growth process of near stoichiometric ablation and transfer of material, and supersaturation on the substrates surface contribute to a near stoichiometric synthesis of complex transition metal oxides, which in turn exhibit a large variety of intersting physical properties, such as high temperature superconductivity and many ferroic properties. These properties are highly sensitive to slight deviation from ideal stoichiometry. Many oxide material that have become of great interest in recent years for there electronic properties contain volatile species such as ruthenium, lead and bismuth, were the volatility, and hence, different sticking mechanisms of these species impede a stoichiometric synthesis. Here, we present a fundamental investigation on the influence of growth parameters on plasma composition, kinetics, which subsequently influence particle substrate interaction, particle sticking and diffusion. Insight on key mechanisms involved in optimized growth conditions will eventually lead to full control over stoichiometry, doping, defect density of PLD thin films and improved thin film properties. An overview on influence of laser fluence and background gas pressure on the spatial evolution of the kinetics and composition of the plasma plume in relation to film characteristics is presented. We use optical self-emission (OSE) imaging and spectroscopy, supported with Laser Induced Fluorescence (LIF) measurements, which gives a unique overview on the quantitative elemental distribution in the plume. It is shown that SrTiO3 film stoichiometry strongly depends on background pressure, where in a relative small pressure range, from 10-2 mbar to 10-1 mbar oxygen pressure, often optimal stoichiometry has been observed, for example, as determined with X-Ray Diffraction (XRD). In this pressure regime, OSE spectroscopy and LIF measurements show that a transition occurs from incomplete to full oxidation of species. This suggests that the oxidation of species of the plasma is a crucial mechanism in the stoichiometric reconstruction of the synthesized oxide thin films.

Authors : M.L. Pace (1), A. Guarnaccio (1), D. Trucchi (2), A. De Bonis (3), R. Teghil (3), S. Orlando (1), D. Mollica (1), G.P. Parisi (1), L. Medici (4), A. Lettino (4), A. Santagata (1)
Affiliations : (1) CNR – ISM Unit of Tito Scalo, Zona Industriale, 85050 Tito Scalo (PZ) - ITALY (2) CNR – ISM Unit of Montelibretti, Via Salaria km 29.300, 00015 - Monterotondo Scalo (RM) - ITALY (3) Dipartimento di Scienze, Università degli Studi della Basilicata,Viale dell’Ateneo Lucano 10, 85100 Potenza - ITALY (4) CNR – IMAA, -Zona Industriale - 85050 Tito Scalo (PZ) - ITALY

Resume : Laser production of noble metal nanoparticles is a rapidly expanding field due to its large applications and strong optical responses. The growth of noble metal nanoparticles (Au, Ag, Cu) and their optical features can vary significantly with the operative conditions used such as laser wavelength, fluence, target-substrate distance and position. The aim of the work here presented is to characterize the direct ejection of the nanoparticles induced by a Ti:S fs laser and relate this to the obtained deposits. With this aim the process was followed by snap shots acquired at different time delays using an Intensified Coupled Charge Device. At laser pulse regimes in the range of few up to tens of J/cm2, it is widely accepted that after the detection of a fast plasma plume component, which is characterized by high electron densities (ca. 10^18 cm-3) and electronic excited ions and atoms lasting about 1x10-6 s, even a secondary much slower emitting component takes place. The latter, whose emission is detectable in the range of 1-100x10-6 s, presents a continuum black-body like emission which is related to the evolution of the hot nanoparticles produced representing more than 80% of the ablated material. In this work it is reported how the laser irradiation features together with the physical-chemical properties of the three noble metal used induce local changes in the characteristics of the obtained deposits such as: 1) chemistry composition, 2) crystal structure and 3) morphology which have been evaluated by SEM, TEM, micro-XRD and XPS ex-situ techniques. It is going to be demonstrated how the fast imaging technique following the dynamics of the hot nanoparticles produced can be an useful in-situ diagnostic tool for predicting the process induced and relating this to the features of the obtained deposits.

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Nanoparticles and nanoscale films : Petar ATANASOV
Authors : R. Serna, J. Toudert and J. Gonzalo
Affiliations : Laser Procesing Group, Instituto de Optica, Serrano 121, Madrid (Spain)

Resume : The complexity of photonic devices is increasing at the same time that its size are decreasing. The current challenge for the development of the next generation devices is to develop materials in the nanoscale that have functionalities such as emission, switching/processing and detection of light and will operate in a wide wavelength range, from the UV to the NIR. Therefore it is necessary to develop techcniques and methodologies that allow to assemble active nanoscale material structures in a plataform suitable for nanophotonics. In this talk I will present the methodology based on Pulsed Laser Deposition that we have developed in our group in order to build optically active materials based in the concept of embedding nano-scale objects into thin film oxides on silicon for CMOS compatible devices. I will show that by choosing the nature/composition, morphology and size of these nanoscale objects in a suitable manner thin films with specific optical responses can be obtained. In this presentation I will show and discuss some examples of our recent work that include efficient nano-hybrid emitters in the near-infrared (Er-doped), wide band emitters in the visible (Eu-doped), and conventional (Ag-based) and non-conventional (Bi-based) plasmonic stuctures suitable for operation in the visible.

Authors : J. C. Abrego-Martínez 1,2, Y. Wang 2, A. Moreno-Zuria 1, J. Ledesma-García 3, L.G. Arriaga 1, M. Mohamedi 2*, F. M. Cuevas-Muñíz 1*
Affiliations : 1 Centro de Investigación y Desarrollo Tecnológico en Electroquímica, 76703 Querétaro, México; 2 Énergie, Matériaux et Télécommunications, INRS, J3X 1S2, Quebec, Canadá; 3 División de Investigación y Posgrado, Facultad de Ingeniería, Universidad Autónoma de Querétaro, 76010 Querétaro, México

Resume : The development of highly methanol tolerant electrocatalyst with an oxygen reduction reaction activity is extremely important for the cathode side of direct methanol fuel cells. In this work, we report the synthesis by pulsed laser deposition technique of platinum layer coated with silver layer, with each layer having a thickness of about 25 nm. The resulting Pt/Ag exhibit clear electrocatalytic activity for oxygen reduction reaction in alkaline solution. More interestingly, it shows no activity for methanol oxidation, in contrast to Pt. In addition, the Pt/Ag catalyst demonstrates selective activity for oxygen reduction reactions even in the presence of concentration of methanol as high as 5 M. This cathode was further tested in a membraneless microfluidic fuel cell using a fuel-oxidant mixed stream, yielding a power density of 0.4 mW cm-2.

Authors : James G. Lunney, Tony Donnelly, Taj Khan, Inam Mirza and Gearoid O’Connell
Affiliations : School of Physics and CRANN, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland

Resume : Laser ablation in vacuum with both nanosecond (ns) and femtosecond (fs) lasers has been used to make nanoparticle (NP) films, where the size and separation of the NPs can to some extent be controlled by variation of the equivalent thickness of the deposit. For ns irradiation the ablation plume is ionised vapour, while fs irradiation leads to the emission of a faster plume of ionised followed by a slower nanoparticle plume. Langmuir probe ion probe measurement and optical spectroscopy have revealed the dynamics of both the plasma and nanoparticle ablation plumes. In particular the temporal variation of temperature and density of the nanoparticle plume was determined from measurement of the absolute spectral radiance of the blackbody-like NP optical emission. The partition of material between atoms, ions and nanoparticles was estimated. The thickness dependence of the nanomorphology of silver NP films was measured for both ns and fs pulsed laser deposition (PLD). The sensitivity of these films for surface enhanced Raman spectroscopy (SERS) was bench-marked against commercial SERS substrates. The possibility of doing PLD of NP films in gas at atmospheric pressure was investigated by: (i) placing the substrate very close to the ablation spot, and (ii) using a gas flow to carry the NP aerosol to a substrate at up to 20 mm from the ablation spot. The nanoparticulate films produced displayed

Authors : R.G. Nikov, N.N. Nedyalkov, P.A. Atanasov, D.B. Karashanova
Affiliations : Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784, Bulgaria Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, G. Bonchev Street, Building 109, Sofia 1113, Bulgaria

Resume : This study presents results on pulsed laser ablation of gold target immersed in different liquids. In the experiments were used double distilled water, ethanol, toluene and chloroform as the liquid medium for the laser ablation. Four different wavelengths: the fundamental (1064 nm), second (532), third (355) and fourth (266) harmonic of a Nd: YAG laser were utilized to produce various colloids. The optical properties of the colloids were evaluated by optical transmittance measurements in the UV–vis spectral ranges. The morphology of the colloidal nanoparticles created and the evaluation of their particles size distribution were investigated by transmission electron microscopy (TEM). The presented method is an alternative to the widely used chemical methods for the preparation of colloidal solutions with certain characteristics allowing their printing with a conventional printer. Printing of such colloids on suitable substrates may find application in the printed electronics to obtain the conductive tracks, and also for the preparation of nanostructured surfaces for surface-enhanced Raman spectroscopy (SERS).

2D layers, interfaces and growth : Thomas LIPPERT
Authors : Guus Rijnders
Affiliations : MESA+ Institute for Nanotechnology, University of Twente, P.O.BOX 217, 7500 AE, Enschede, The Netherlands

Resume : Diverse electronic phases in complex oxide materials such as superconductivity, magnetic phases and ferroelectricity are intimately coupled to the crystal symmetry. Atomic layer controlled growth of oxide heterostructures offers a flexible route to tune the symmetry and this has been shown to give rise to many unusual emergent properties that are absent in the original materials. Using such atomic layered growth, we have fabricated perovskite heterostructures in which the altered symmetry is found to propagate over a long range. The interfacial octahedral coupling induced symmetry can even propagate throughout the total thickness of epitaxial films. Desired symmetries of perovskite heterostructures are furthermore achieved by engineering the substrate symmetry, for example by introducing a buffer layer with different symmetry. Our results demonstrate that the long range symmetry propagation can effectively control metal to insulator transition, as well as magnetic ordering. In this contribution, I will focus on the fabrication of epitaxial heterostructures, the analysis of the crystal symmetry using x-ray diffraction, and high-resolution STEM, as well as resulting properties of magnetic phases.

Authors : F. Antoni1, E. Fogarassy1, F. Le Normand1, T. Szorenyi2 and J. Hulik1
Affiliations : 1 ICube, D-ESSP, 23 rue du Loess, 67037 Strasbourg France 2 Department of Optics and Quantum Electronics, University of Szeged, P.O. Box 406, H-6701 Szeged, Hungary

Resume : In this paper, we present our experience for almost 30 years in carbon based thin films obtained by the Pulsed Laser Deposition (PLD) technique. During all those years, the PLD technique matured to a well-established laboratory technique for thin film production. PLD offers a very high versatility from which carbon based thin films take many advantages. In first, our experience in hydrogen free Diamond-Like Carbon (DLC) layers deposition permits to develop a few collaborations in the medical domain. The physicochemical properties of the obtained thin films, which are just beneath to those of diamond are adding biocompatibility and very low roughness. In our much recent work, we also use DLC as buffer layers to produce conductive graphene on top of a fully transparent and insulating multilayered structure of DLC/quartz. The feasibility and obtained performances of graphene formation on DLC are currently explored in great details in order to develop an alternative to ITO for flat panel display technology. Moreover, we explored the feasibility to produce carbon-nitride and well as boron-carbide thin films for tribological purposes. For those specific applications, we investigate the reactive PLD technique in which the ablated carbon plasma interacts with various gaseous environments in order to control the stoichiometry and physicochemical properties of the deposited layers.

Authors : Matjaž Spreitzer,1 Dejan Klement,1 Zoran Jovanović,1,2 Daniel Diaz, 1 Tjaša Parkelj,1 and Danilo Suvorov1
Affiliations : 1 Advanced Materials Department, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia 2 Laboratory of Physics, Vinča Institute of Nuclear Sciences, University of Belgrade, 11001 Belgrade, Serbia

Resume : The deoxidation and passivization of a silicon surface represent one of the most important steps in the successful integration of functional oxides with silicon. Due to its reactivity and dissimilar properties with respect to oxides, silicon surfaces are conditioned using different buffer systems. Among them SrO- and Sr-based buffers have proved highest chemical and structural compatibility. However, the achievements have not been commercialized as molecular beam epitaxy, which has been most often used to interface the materials is industrially less appropriate. In our work pulsed laser deposition (PLD) is used to integrate oxides with silicon. We showed the ability to prepare highly-ordered sub-monolayer SrO- and Sr-based structures on silicon surface, including two-domain (2×3)+(3×2) pattern at 1/6 ML Sr coverage as determined by the reflection high-energy electron diffraction (RHEED) technique. On the passivated silicon surface epitaxial layers of SrTiO3 have been grown by the method of kinetically controlled sequential deposition, with out-of plane relationship of STO(001)║Si(001) and in-plane relationship of STO[110]║Si[100]. In the talk most critical deposition parameters will be discussed and related to the interface quality.

Authors : C. Maddi ; T. Tite ; V. Barnier* ; F. Bourquard, S. Reynaud ; J. –Y. Michalon ; A. S. Loir ; K. Wolski* ; C. Donnet ; F. Garrelie
Affiliations : Université de Lyon (France), Laboratoire Hubert Curien (UMR 5516), Université Jean Monnet, 42000 Saint-Étienne, France * Laboratoire Georges Friedel (UMR 5307), Ecole Nationale Supérieure des Mines, 42023 Saint-Etienne, France

Resume : Graphene and its derivative are attracting a lot of attention today due to their growing range of applications. This highlights the need to look for new synthesis routes, which allow better tailoring of graphene based materials properties as well as simplifying synthesis methods. In particular, nitrogen doping appears as an interesting option to modify the electrochemical properties of graphene. Meanwhile, the pulsed laser deposition of graphene proved efficient to produce multilayer graphene for applications in the domain of biosensors. In this work, N-doped graphene synthesis was performed through femtosecond pulsed laser ablation of graphite in a nitrogen environment, and vacuum annealing of the deposited material. Nitrogen doping and structural properties of the material were evaluated via different characterization techniques. C-N bonding configurations as well as N contents have been evaluated by X-ray photoelectron spectroscopy. Raman mapping showed the decrease of the 2D peak intensity compared to pure graphene, as well as a decrease in crystalline size (La), allowing to check the homogeneity of the doping. XPS studies showed that N atoms appear to be mainly in the pyridinic type of bonding, with contents going up to 3 % atomic. This kind of bonding, coupled with the versatility of this fast and low temperature approach, makes the produced N-doped graphene a promising materials for electrochemichal sensors, targeting biosensors applications.

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Thin films and heterostructures of functional materials II : Robert EASON
Authors : Corinne Champeaux1, Michael Gaudin, Rafika Zaabi, Jean-Christophe Orlianges1, Aurelian Crunteanu2, Catalin Constantinescu1, Frédéric Dumas-Bouchiat1
Affiliations : 1Univ. Limoges, CNRS, SPCTS UMR 7315, 12 rue Atlantis, F-87068 LIMOGES, France 2Univ. Limoges, CNRS, XLIM UMR 7252, 123 Av. Albert Thomas, F-87060 LIMOGES, France

Resume : Nanosecond-laser ablation processes are now widely recognized as powerful technologies in the fabrication of thin films with complex stoichiometry and good required properties using the well-known Pulsed Laser Deposition (PLD). In multitarget configuration, depending on the irradiation time on the different targets, PLD leads to multilayers deposition as well as doping. Moreover due to the specific characteristics of the laser-matter interaction in nanosecond regime, laser ablation is a good candidate to synthesize nanoparticles with controlled size and also narrow size distribution. A process based on a free nanoparticles (NPs) generator coupled to a PLD set up, designed and developed in our lab, offers the possibility to fabricate nanocomposite materials. Using separately, simultaneously or sequentially the generator and/or PLD, this set up allows respectively NP-stacks, nanocomposite thin films with embedded NPs or multilayers NPs/thin films. In this paper, the potentialities of these promising ablation processes are exploiting for the fabrication of new thin-films materials with tunable functionalities. Studies concern vanadium dioxide (VO2) and derivated thin films and their integration in microelectronics and optics devices. VO2 is a "smart" material with properties that are sensitive to physical external stimuli. It presents a first order metal to insulator transition (MIT) at 68°C, characterized by abrupt changes in both resistivity (5 orders) and near-IR optical transmission (70%). Here its physical properties have been managed by doping (Cr, W, Au) and by the size effect of switching domains.

Authors : Nicu D. Scarisoreanu, Maria Dinescu
Affiliations : National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-16, RO 77125 Magurele, Romania

Resume : Since its first demonstration in 1965, Pulsed Laser Deposition (PLD) as thin films growth technique plays an important role, due to the high flexibility which allows obtaining layers from materials with complex stoichiometries. It is in this field of application where the most significant achievements are reported. In this work results on Pulsed Laser Deposition of three important multifunctional oxides, SBN, BFO and BT are presented. Strontium barium niobate SrxBa1-xNb2O6 (0.25 ≤ x ≤ 0.75, SBN) is a ferroelectric solid solution with tetragonal tungsten bronze structure. SBN exhibits a large value of electro-optic (EO) and pyroelectric coefficients and it is a ferroelectric relaxor. Bismuth ferrite BiFeO3 (BFO) is by far the most promising and intensively investigated multiferroic material because of a wide range of applications in nonvolatile memories, spintronics, piezoelectric devices etc. BaTiO3 (BT) ferroelectric perovskite is commonly used to develop new lead-free piezoelectric materials. By doping the above mentioned oxides with different elements, (SBN with Ca, BFO with Y and BT with Ca and Zr), and using different substrates inducing strain engineering in the respective layers, significantly enhanced dielectric/ferroelectric/multiferroic properties can be reached.

Authors : J. Hulik 1,4, F. Le Normand 1, F. Antoni 1, F. Aweke 1, D. Muller 1, S. Zafeiratos 2, W. Luo 2, P. Pfeiffer 3, P. Veis 4
Affiliations : 1 ICube, MaCEPV, 23 rue du Loess, 67037 Strasbourg, France; 2 ICPEES, ECPM, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France; 3 ICube/IPP, Pôle API, 300, Boulevard Sébastien Brant, 67412 Illkirch, France; 4 Comenius University, Faculty of Mathematics, Physics and Informatics, Department of Experimental Physics, Mlynská dolina F1, 84248 Bratislava, Slovakia

Resume : Graphene thin films on Diamond-like carbon (DLC) films have been obtained on transparent substrates like quartz or glass by pulse laser deposition (PLD) of carbon at ambient temperature followed by either thermal annealing performed in Ultra High Vacuum condition up to 1273 K. The surface formation of a graphene-like film on top of the DLC, soon experimentally shown in Appl. Phys. A, Materials Science & Processing, 71, 433–439 (2000), has been investigated as a function of many parameters of the PLD and post-PLD processes (like laser fluence, DLC thickness, annealing temperature). The roughness of the films was find lower than 1 nm set over a rather large surface area. The density of the carbon has been measured both by XPS and Nuclear Reaction Analyses (NRA). The formation of graphene films on top of DLC have been characterized by X-ray photoemission (XPS) and Raman scattering. Under optimized conditions these films can exhibit high surface conductivity, optical transmission and work function performances, so that it can be achieved a high figure of merit (conductivity of transparency) as transparent conductors.

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Poster session : Salvatore AMORUSO, Matjaz SPREIZER, Michael LORENZ, Rosalia SERNA
Authors : J. JJ Nivas 1,2, Zhenming Song 1,3, F. Cardano 1, A. Rubano 1,2, A. Vecchione 4, R. Fittipaldi 4, D. Paparo 5, X. Wang 2, L. Marrucci 1, R. Bruzzese 1,2, S. Amoruso 1,2
Affiliations : 1) Dipartimento di Fisica "Ettore Pancini", Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli, Italy. 2) CNR-SPIN UOS Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli, Italy. 3) School of Science, Tianjin Polytechnic University, Binshuixi Road 399#, Xiqing District, Tianjin, 300387 P. R. China.4) CNR-SPIN, UOS Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (SA), Italy. 5) National Research Council, Institute of Applied Science & Intelligent Systems (ISASI) ‘E. Caianiello’, Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy.

Resume : There is increasing interest for surface structures at the micro- and nano-scale. Femtosecond laser surface structuring with a Gaussian beam has already distinguished itself as a versatile method to fabricate surface structures on metals and semiconductors. In this communication, we report our recent results on femtosecond laser surface structuring obtained with both Gaussian and optical vortex (OV) beams. The OV are cylindrical vector beams with a state of polarization (SoP) that varies spatially retaining an axial symmetry and offer the possibility to further extend and control the characteristics of the surface structures. We will present a rather complete analysis on the generated structures (e.g. ripples and grooves) as a function of the number of pulses N and laser pulse energy Ep. In particular, we address the surface evolution from the initial stage of surface modification (low N) to the complete development of the structure (high N). Moreover, we discuss the possibility offered by OV beams. Our findings suggest that direct femtosecond laser surface structuring is a versatile approach both to generate a variety of surface patterns and to characterize complex femtosecond laser beams. This, in turn, allows proposing a physical mechanism interpreting the initial stage of surface evolution, the ripples creation and the grooves generation at the various stage of the structuring process.

Authors : L. Floroian1, C. Ristoscu2, M. Galca3, N. Mihailescu2, M. Badea1, Monica Moscatelli4, Gabriele Candiani4, Roberto Chiesa4, I.N. Mihailescu2
Affiliations : 1 Transilvania University of Brasov, 29 Eroilor Blvd, 500036, Brasov, Romania 2 National Institute for Lasers, Plasma and Radiation Physics, M?gurele, Romania 3 "Carol Davila" University of Medicine and Pharmaceutics, 8 Eroilor Sanitari Blvd, 50471, Bucharest

Resume : Ayurvedic medicine is one of the world?s oldest medical systems. It is an example of a coherent traditional system which have a time tested and precise algorithm for medicinal plant selection, based on several ethnopharmacophore descriptors whose knowledge endows the user to adequately choose the optimal medicinal plant for the treatment of certain pathology. This work tries to link traditional knowledge with biomedical science by using traditional ayurvedic plants with antimicrobial effect in manufacture of thin films for implant protection. We report on the transfer of novel polymer-antimicrobial plants extract-bioactive glass composites by matrix-assisted pulsed laser evaporation to uniform thin layers onto stainless steel implant surfaces. Influence of the deposition process on the structure of nanomaterials was studied. The targets were prepared by freezing in liquid nitrogen of mixtures containing polymer and plants extract reinforced with bioglass powders. The cryogenic targets were submitted to multipulse ablation with an UV KrF* (?=248 nm, ? ~ 25 ns) excimer laser source. The main advantages with this coating are multiple: stopping any leakage of metal and metal oxides to the biological fluids and eventually to inner organs (by polymer use), speeding up osteointegration (by bioactive glass use), antimicrobial effect (by ayurvedic plants extracts use) and decreasing of the implant price (by cheaper stainless steel use). ACKNOWLEDGEMENT: LF and MB hereby acknowledge the structural founds project PRO-DD (POS-CCE, O.2.2.1., ID 123, SMIS 2637, ctr. No 11/2009) and “ Bursa universitatii 2016” for providing the infrastructure used in this work.

Authors : N. Jedrecy(1,2), C.Hebert(1,2), J. Perrière(1,2), E. Millon(3), M. Nistor(4), X. Portier(5), R. Perez-Casero(6)
Affiliations : (1) Sorbonne Universités, UPMC Univ Paris 06, UMR 7588, INSP, 4 Place Jussieu, F-75005 Paris, France (2) CNRS, UMR 7588, INSP, 4 Place Jussieu, F-75005 Paris, France (3) Univ Orleans, UMR CNRS 7344, GREMI, 14 Rue Issoudun, F-45067 Orleans 2, France (4) National Institute for Lasers, Plasma and Radiation Physics, L22 POB MG-36, 77125 Bucharest, Romania (5) CIMAP, CEA/CNRS UMR 6252/ENSICAEN/UCBN, 6 Bld du Maréchal Juin, 14050 Caen Cedex, France (6) Departamento de Fisica Aplicada, Facultad de Ciencas, Universidad Autonoma de Madrid, C/Francisco Tomas y Valiente 7, 28049 Madrid, Spain

Resume : Pulsed-laser deposition (PLD) is an anisotropic process that leads to non-uniformities in film thickness and composition. Recently non-uniformities in crystalline structure (cell axis parameter, texture) of films were evidenced. In this work, we have investigated nanocomposite Zn1-xFexO (0.3 < x < 0.8) oxide films grown by PLD under vacuum conditions (10-7 mbar), in the room temperature to 500°C range. By the complementary use of Rutherford backscattering spectrometry and X-ray diffraction analyses, the formation of nanocomposite oxide films was evidenced through the presence of both wurtzite (ZnO-like) and spinel (Fe3O4-like) phases in the films. The high anisotropic character of plume expansion during PLD leads to large non-uniformities in the respective concentration of wurtzite and spinel phases across the film surface. A correlation was established between the film composition, structural phases and their physical properties [1,2]. Such films that present original optical and electrical characteristics could be of interest in photocatalysis, while the nanocomposite aspect could be used in thermoelectric applications. [1]- J. Perrière, C. Hebert, M. Nistor, E. Millon, J. J. Ganem, N. Jedrecy, J. Mater. Chem. C 3, 11239 (2015). [2]- N. Jedrecy, C. Hebert, J. Perrière, M. Nistor, E. Millon, J. Appl. Phys. 116, 213903 (2014).

Authors : Ru.G. Nikov, A.O. Dikovska, N.N. Nedyalkov, P.A. Atanasov
Affiliations : Institute of Electronics, Bulgarian Academy of Sciences, Tsarigradsko Chaussee 72, Sofia 1784, Bulgaria

Resume : In this study we demonstrate fabrication of Au nanostructures by direct deposition of Au nanoparticles and aggregates produced by pulsed laser ablation in air at atmospheric pressure. Due to the high density of the ambient atmosphere the plasma plume is strongly confined. At these conditions the nanoparticle formation occurs in the plume by intensive collisions of the spices and condensation of the ablated material. The ablation process of Au is performed by nanosecond laser pulses delivered by Nd:YAG laser system as the ablated material is deposited on quartz substrate in air environment. Characteristics of the fabricated structures are studied as a function of the laser wavelength, the laser fluence and the geometry of the deposition process. The complex structure observed in the fabricated samples suggests that they could be successfully used in applications as surface enhanced Raman spectroscopy (SERS) and sensors devices.

Authors : C. Tchiffo-Tameko (1), C. Cachoncinlle (1), J. Perriere (2,3), M. Nistor (4), E. Millon (1)
Affiliations : 1 GREMI, UMR 7344 CNRS-Université Orléans, 45067 Orléans Cedex 2, France; 2 Sorbonne Universités, UPMC Université Paris 06, UMR 7588, INSP, 75005, Paris, France 3 CNRS, UMR 7588, INSP, 75005, Paris, France 4 NILPRP, L 22 P.O. Box. MG-36, 77125 Bucharest-Magurele, Romania

Resume : Electrical and optical properties of TiOx films co-doped with Nd and Nb are reported. The role of oxygen vacancies on the physical properties is evidenced. The films are grown by pulsed-laser deposition onto (001) sapphire and (100) silicon substrates held at 700°C. Either stoichiometric (TiO2) or highly oxygen deficient (TiOx with x<1.6) thin films are grown by adjusting the oxygen partial pressure at 10-1 and 10-6 mbar, respectively. 1%Nd-1%Nb, 1%Nd-5%Nb and 5%Nd-1%Nb co-doped TiO2 were used as bulk ceramic target. Composition, structural and morphological properties of films determined by Rutherford backscattering spectroscopy, X-ray diffraction and scanning electron microscopy, are correlated to their optical (UV-Visible transmission and photoluminescence) and electrical properties (resistivity at room temperature). The most intense Nd3 emission in the IR domain is obtained for stoichiometric films. The oxygen pressure during the growth allows to tune the optical and electrical properties: insulating and highly transparent (80% in the visible range) Nd/Nb codoped TiO2 films are obtained at high oxygen pressure, while conductive and absorbent films are grown under low oxygen pressure (10-6 mbar).

Affiliations : 1 Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS/Université de Rennes 1, Campus de Beaulieu, 35042 Rennes, France ; 2 Unité de Dynamique et Structure des Matériaux Moléculaires (UDSMM), Université du Littoral Côte d'Opale, 50 rue F. Buisson, BP717, 62228 Calais, France ; 3 ScanMAT – CMEBA, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France ; 4 SIMTRONICS SAS, 792, Av. de la Fleuride, BP 11061, 13781 Aubagne Cedex, France

Resume : Nowadays, gas detection mainly uses optical sensors, lead-based electrochemical sensors and catalytic sensors based on platinum. However, due to the still more restricted environmental European directives and to the increasingly strong economic and technical constraints, a new generation of sensors becomes a necessity. In the case of the detection of toxic and flammable gases in industrial sites, lead-free sensors based on metal-oxide semiconductors could meet this urgent need. For that reason, the industrial partner involved in Ospegaz project, whose one of the main markets is related to the detection of toxic gas on oil production sites, is interested in such gas sensors dedicated in particular to H2S detection. In this context, ZnO thin films were deposited by pulsed laser deposition on SiO2/Si substrates. The influence of deposition conditions on microstructure and on detection properties of the films was studied. ZnO thin films, with interdigitated electrodes deposited on top, were directly integrated in commercial sensor casings. Measurements under gas flow were performed on these ZnO sensors and on commercial semiconductor gas sensors for comparison. ZnO sensors give a moderate sensitivity (R/R0 = 0.25) at 400°C under 100 ppm H2S for a non-yet optimized sensor volume, whereas better response times than commercial sensors were observed. All the results related to the sensitivity study and sensor responses (response time, recovery time, repeatability) will be presented. French research project titled OSPEGAZ (2012-2015) funded by the French Agency of Research (ANR)

Authors : C. Cachoncinlle (1), E. Millon (1), M. Nistor (2)
Affiliations : (1) GREMI, UMR 7344 CNRS-Université Orléans, 45067 Orléans Cedex 2, France; (2) NILPRP, L 22 P.O. Box. MG-36, 77125 Bucharest-Magurele, Romania

Resume : ZnO thin films are been largely studied due to their exceptional ability to produce photons in the UV spectral domain. Furthermore, ZnO was revealed to be an excellent semiconductor for the generation of random lasing at relatively low threshold. In this study, we report on imaging of the diffuse area produced by the scattering of the light that leads to the random lasing phenomenon. Our films were grown using well-established pulsed-laser deposition at 248 nm. The laser beam was focused onto a ZnO ceramic rotating target. The film growth was controlled by adjusting both surrounding oxygen pressure (from 102 to 10-4 Pa) and substrate temperatures (300-1000K). We used sapphire (001) and MgO (100) single crystal substrates. Random lasing is evidenced by high-resolution emission spectroscopy when the films are optically pumped by a pulsed 266 nm NdYAG laser. Above threshold, the spectral linewidths of the so-called “spikes” features characteristic of the random lasing are smaller than 50 pm. Luminance maps of the diffusing area are recorded by the a CCD Camera. The films that produce random lasing exhibit a drastic larger emission area than the simple laser pump spot size while no emission is observed for the non-lasing films. This observation is correlated with absorption coefficient calculation to tentatively explain the systematic appearance of the random lasing on the red wings side of the near band edge of the photoluminescence.

Authors : F. Cissé1,2, A. Waroquet1, X. Castel2, V. Demange1, S. Ollivier1, S. Députier1, V. Bouquet1, R. Sauleau2, L. Joanny3, M. Guilloux-Viry1
Affiliations : 1 ISCR, UMR-6226/Université de Rennes 1, Campus de Beaulieu, 35042 Rennes, France 2 IETR, UMR-6164/IUT de Saint-Brieuc/Université de Rennes 1, 18 rue Henri Wallon, 22004 SAINT-BRIEUC & Campus de Beaulieu, 35042 Rennes, France 3 ScanMAT – CMEBA, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France

Resume : Ferroelectric thin films are intensively studied for the realization of microwave tunable devices as their dielectric permittivity can be driven by an external DC electric field, however with a limitation due to high dielectric loss. Their piezoelectric properties are another motivation for microwave applications requiring reconfigurability, via piezo-MEMS. In this frame, ferroelectric potassium niobates are potential candidates, as lead-free piezoelectric material, as an alternative for PZT. In this work, thin films from the system (K,Na) – (Nb,Ta) – O (KNN) have been grown by Pulsed Laser Deposition (KrF excimer laser) on sapphire substrates. KNN thin films were deposited from a K0.5Na0.5NbO3 target and then characterized by X-ray diffraction and scanning electron microscopy before their implementation in coplanar waveguide (CPW) devices (stub resonators and transmission lines). The dielectric permittivity and dielectric loss were retrieved from measurements on transmission lines whereas the tunability and global loss were determined using the stub resonators. The dielectric permittivity is about 110 at 10 GHz, and a tunability of about 5 % is obtained for a resonance frequency close to 18 GHz. A comparison with K0.5Ta0.5Nb0.5O3 (KTN) thin films that we have previously studied will be presented. Whereas the tunability obtained with KTN is higher than that displayed with KNN, the global loss remains lower with KNN, which is a promising result for further studies.

Authors : M.E. Koleva, N.N. Nedyalkov, P.A. Atanasov
Affiliations : Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee blvd., Sofia 1784, Bulgaria

Resume : The room-temperature laser synthesis of porous plasmonic nanocomposites is presented. The laser irradiation with UV nanosecond laser pulses has been used to modify the microstructural and optical properties of PLD grown Ag/ZnO layers. A high surface to volume ratio and formation of plasmonic nanoparticles are achieved. The effect of silver concentration and laser annealing procedures on the morphology and optical properties of Ag/ZnO embedded nanostructures are studied. The influence of laser irradiation on the microstructure and plasmon resonance absorption of the samples is investigated at different number of laser pulses. The composite systems demonstrated interesting plasmonic properties, which can be easily tuned by controlling the nanostructures morphology from nanochains to nanoparticles. The experimental results follow the results predicted from the theoretical calculations based on the generalized multiparticle Mie (GMM) theory for the extinction efficiency of AgNPs in ZnO environment. The morphology of the samples annealed at higher number of laser pulses strongly depends on the silver content. Composite nanostructures are found to exhibit enhanced resonance absorption after the laser annealing procedures, predominantly for the samples with higher silver concentration. The laser processing technique is an exciting value for tailoring structural and functional properties of composite nanostructures with improved performance for various applications.

Authors : A. Og. Dikovska, G. Atanasova, T. Dilova, P. Stefanov, P. A. Atanasov
Affiliations : A. Og. Dikovska; P. A. Atanasov; Institute of Electronics, Bulgarian Academy of Sciences,72 Tsarigradsko Chaussee, Sofia 1784, Bulgaria G. Atanasova; T. Dilova; P. Stefanov Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia, Bulgaria

Resume : Gas sensors based on one-dimensional metal oxide nanostructures (such as nanowires, nanorods, and nanobelts) have demonstrated enhanced sensing properties, not only due to their large surface-to-volume ratio, but also because of their suitable physical and chemical properties. Among metal oxides, the advantageous features of ZnO, such as high electron mobility and chemical and thermal stability make it an appropriate material for gas sensing applications. Various techniques have been applied for deposition of ZnO nanostructures. Among them, the pulsed laser deposition (PLD) technique is interesting because it offers an easy way to add other elements for alloying or for doping purposes. An important point is that PLD gives the advantage of carrying out the growth in a high oxygen partial pressure for a better control of a possible oxygen deficiency. The possibility to tune the deposition parameters in order to control the morphology of the deposited films, for example passing from smooth to rough films or to nanostructures, is a fundamental issue; solving it will assist in their functional use in the different technological fields. In this work, we present the fabrication by PLD of ZnO nanostructures suitable for gas sensor application. Noble metal nanoparticles (NPs), namely Au and Pd, were deposited on the ZnO nanostructures. Our attention was focused on the influence of the noble metal (type of noble metal, NPs fabrication method, size and NPs distribution) on the gas sensing properties of the ZnO samples under pollutants and toxic gas exposure (CO, NH3, and NO2). It was found that the Au nanoparticles on the surface of a ZnO sensor element enhanced the response to CO gas, while the Pd nanoparticles can be selectively used for NH3 gas detection.

Authors : N.Nedyalkov1,2, P.A. Atanasov2, Y. Nakajima1, A. Takami1, M. Terakawa1
Affiliations : 1Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi Kohoku-ku, Yokohama-shi, Kanagawa-ken, 223-8522, Japan 2Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784, Bulgaria

Resume : In this work results on laser assisted formation of gold nanoparticles in glass are presented. The sample material is borosilicate glass obtained by conventional melt quenching method. In the fabrication stage AuCl3 is added in order to obtain gold ion doped material. The produced glass samples are then irradiated by laser pulses with a wide variety of parameters – wavelength, fluence, pulse duration. At certain conditions femtosecond laser radiation induces defects associated with formation of color centers in the material. After annealing of the samples the irradiated areas express red color whit clear dip in the transmission spectra. This effect is related to formation of gold nanoparticles and their optical properties defined by plasmon resonance. The optical properties of the irradiated areas are found to depend on the laser processing parameters. Irradiation with nanosecond laser pulses may also induce color change of the glass, but at laser fluences where a permanent damage of the material is observed. The properties of the material at the processed areas are studied on the basis of generalized multiparticle Mie theory that is used to correlate the experimentally obtained optical spectra and the characteristics of the nanoparticles. The influence of the processing condition on the characteristics of the formed particles and the mechanism of their formation are discussed. This method can be used in fabrication of 3D nanoparticles systems in transparent materials that can be applied in the design of new optical components as metamaterials and in plasmonics.

Authors : 1 Nadya E. Stankova, 1 Ivan G. Dimitrov, 1 Petar A. Atanasov, 2 D. Kovacheva, 3 At.N. Tzonev, 1 Toshko R. Stoyanchov
Affiliations : 1 Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Blvd., Sofia 1784, Bulgaria, 2 Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. Georgi Bontchev str. Bl.11, 1113 Sofia, Bulgaria, 3 Department of Solid State Physics and Microelectronics, Faculty of Physics, University of Sofia, 5 J. Bouchier Blvd., Sofia, Bulgaria

Resume : The evolution of the crystal, the microstructural and the optical properties of pulsed-laser deposited TiO2 films, investigated by X-ray diffraction, atomic force microscopy, scanning electron microscopy, optical transmittance and m-line spectroscopy measurements are reported. The samples were grown on (0 0 1) SiO2 substrates at temperatures from room temperature to 600 C in oxygen environment. The films grown up to 400 C are amorphous or consist of very fine crystallites. Crystalline films consisting of single anatase or anatase and rutile phases were obtained at temperatures higher than 400 C. Tendency towards columnar-like growth morphology was observed in all samples. All films revealed single- or multimode waveguiding and optically anisotropic properties. Considerable effective birefringence readings were estimated for the amorphous films. The observed optical anisotropy is much more related to the columnar microstructure rather than the crystalline features of the films. Highbirefringence materials are strongly desirable because of their potential applications in improved optical data storage and data transfer in communications technology.

Authors : E.Venkata Ramana1*, M.A.Valente1, B. W. Lee2 and C. U. Jung2
Affiliations : 1 I3N-Aveiro, Department of Physics, University of Aveiro, Aveiro-3810 193, Portugal. 2 Department of Physics, Hankuk University of Foreign Studies, Yongin Kyoungki-do 449-791, Korea.

Resume : Materials that combine properties of ferroelectricity and ferromagnetism have attracted the attention of researchers in recent years in view of their applications in high-density, stable nanoscale non-volatile memory elements, spintronics and actuators. The control of different ferroic properties by electrical or magnetic fields of stimulus enables the tuning of multiple state memory devices. One of the popular approaches to induce magnetism in a ferroelectrics and the resultant coupling is the introduction of magnetizable ions at A- or B-sites of the perovskite lattice. In the present work we attempt to study the electrical and magnetic behavior of highly Fe-doped lead-free ferroelectric thin films. Epitaxial Fe-doped (40 mol. %) BaTiO3 (BTFO) thin films were grown on single crystalline STO (001) substrate by the pulsed laser deposition (a KrF excimer laser, Lambda Physik, λ=248 nm) to study the structural, electrical and magnetic behavior. The films grown at substrate temperatures in the range 630-770 oC under oxygen partial pressure <1x10-6 Torr exhibited secondary phases while those grown at higher oxygen pressures showed high purity. The surface morphology also showed systematic changes, roughest surface for the film having secondary phases and a very flat surface for the film grown at an optimum oxygen pressure of 10 mTorr. Room temperature Polarization-electric field measurements in BTFO thin films grown on SrRuO3 buffered STO exhibited large leakage current and a switchable ferroelectric response was observed at 80 K. The doping induced leakage current and its mechanism are analyzed in the temperature range 80-320 K. BTFO films exhibited room temperature ferromagnetism with saturation magnetization of 14.6 emu/cm3. Magnetic field induced capacitance and polarization are presented to elucidate the magnetoelectric coupling.

Authors : P. Písařík 1 2 *, M. Jelínek 1 2, J. Remsa 1 2, J. Mikšovský 1 2, K. Jurek 2, and Š. Kubinová 3
Affiliations : 1 Czech Technical University in Prague, Faculty of Biomedical Engineering, nam. Sitna 3105, 272 01 Kladno, Czech Republic 2 Institute of Physics ASCR v.v.i., Na Slovance 2, 182 21 Prague 8, Czech Republic 3 Institute of Experimental Medicine ASCR, Videnska 1083, 14220 Prague 4, Czech Republic * E-mail:, tel.: 420 224 358 798

Resume : Silver doped diamond-like carbon layers (Ag-DLC) were deposited on silicon (Si 100) and fused silica substrates by dual pulsed laser ablation (dual-PLD) using two KrF excimer lasers and two targets (graphite and silver). The composition and structure was analyzed using wavelength-dependent X-ray spectroscopy and X-ray diffraction. The Ag content increased from 0 at.% to 9.34 at.%. The topology and surface properties as roughness of layers were studied using scanning electron microscopy and atomic force microscopy. With the silver concentration increase the roughness and the number of droplets increased. With increasing of silver content the transmission of layers, measured in the range from 200 nm to 1100 nm, decreased. Three liquids (ethylene glycol, diiodomethane and deionized water) were used to measure contact angle and for the calculation of the surface free energy (SFE). Antibacterial properties were studied using gram positive and gram negative bacteria. Our results demonstrate that the Ag doped DLC films are potentially useful biomaterials having good topology and antimicrobial characteristics.

Authors : J. Miksovsky12, M. Jelinek12, P. Pisarik12, T. Kocourek12, J. Remsa23, K. Jurek2
Affiliations : 1 Czech Technical University in Prague, Faculty of Biomedical Engineering, Czech Republic; 2 Institute of Physics ASCR, Prague, Czech Republic; 3 Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Czech Republic

Resume : Diamond-like carbon (DLC) films are broadly studied for many purposes in many branches. For improvement of their mechanical properties and biocompatibility many deposition techniques and dopants were tested. This study is focused on changes in mechanical and corrosion behaviour with various amount of titanium in DLC/Ti thin films. Used technique is based on pulsed laser deposition (excimer laser, KrF, λ = 248 nm) combined with DC magnetron sputtering. Laser fluency was 8 J/cm2, power of magnetron was from 40 to 300 W. We studied behaviour of layers for Ti concentration from as 1at% to 25at%. Si(100) and Ti6Al4V alloy were used as substrates. Prepared films were characterized with focus on their basic physical properties, such as crystallinity by XRD, morphology by AFM and profilometry, chemical bonding nature by WDX, surface free energy by contact angle. Hardness, Young's modulus and microadhesion were studied by nanoindentation. Makro adhesion was studied up to 50 N, there was growth in critical load with higher Ti concentration observed and improvement in wearability as well. The content of sp3 bonding decreased with increased Ti and increased with forming of TiC phase. Special focus was on tribological properties. Friction and wearability were evaluated under various condition. Corrosion rates were measured as function of Ti concentration. Biology tests for determination of increasing Ti concentration influence in the layers on changes in bioactivity were studied.

Authors : F. Bourquard, O. Diop, F. Garrelie
Affiliations : Université de Lyon (France), Laboratoire Hubert Curien (UMR 5516), Université Jean Monnet, 42000 Saint-Étienne, France

Resume : The properties of thin films generated by Pulsed Laser Deposition are highly dependent on the kinetic properties of the laser ablation plume. In the context of femtosecond Pulsed-Laser Deposition, the multimodal kinetic distribution of the various plume species (ions, neutral atoms, molecules…) makes it difficult to precisely control the fundamental deposition processes. Classic laser parameters, such as wavelength and fluence appear limited to perform a precise control of the kinetic properties. However, it has been shown that using double femtosecond pulses or picosecond pulses could significantly affect the plume kinetics during graphite ablation. In this work, the intensified CCD imaging technique was used in conjunction with spectral bandpass filters to study the ablation plume of metals. Using both temporal and spectral resolution, it is possible to observe the spatial expansion of emission lines corresponding to various energy levels of atoms and ions in the plume, and to obtain a detailed map of the plume excitation. Several temporal pulse shapes were used, going from classic double and long pulses to more complex ones (mixing several pulses with different energies and durations) in order to modify the plume kinetics distributions. The result highlight both the fundamental processes of ultrashort laser matter interaction and future possible applications of temporal pulse shaping.

Authors : N.D. Scarisoneanu1, V. Ion1, A. Moldovan1, A. Andrei1, A.I. Bercea1, F. Craciun2, R. Birjega1 and M. Dinescu1
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 : The new non-lead ceramic (Ba1−xCax)(ZryTi1−y)O3 (BCZT), based on BaTiO3 system, were intensively developed in last years in doped or undoped bulk form. Varying the Ba/Ca and Zr/Ti ratios a huge dielectric constant and piezoelectric coefficient up to d33~650 pC/N were obtained. The phase diagram of (Ba1−xCax)(ZryTi1−y)O3 (BCZT) system exhibit a morphotropic phase boundary (MPB) point around x/y = 0.15/0.10, where the rhombohedral and tetragonal phases coexist. For BCT-BZT system the ferroelectric, dielectric and piezoelectric properties are maximized at MPB point. The dielectric and piezoelectric properties can be improved by tailoring the space of constraints (i.e epitaxial strain). In present work, we present the BCZT thin films with tailored properties for different functionalities needed in photonics, electronics and biotechnology. Using Pulsed Laser Deposition (PLD) technique, the role of epitaxial strain and fine stoichiometric changes induced into the BCZT thin films on the enhancement of electrical properties is revealed. Thin films of (Ba1−xCax)(ZryTi1−y)O3 grown on pure and Nb doped SrTiO3 substrate were investigated by X -ray diffraction, High resolution transmission electron microscopy (HRTEM), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Spectroscopic Ellipsometry (SE) and by dielectric spectroscopy techniques

Authors : V. Ion1, N.D. Scarisoreanu1, F. Craciun2, R. Birjega1, A. Bonciu1 A. Moldovan1, V. Dinca1, L.E. Sima3, M. Icriverzi3, A. Roseanu3, M. Dinescu1
Affiliations : 1National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Romania 2CNR-ISC, Istituto dei Sistemi Complessi, Area della Ricerca di Roma-Tor Vergata, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy 3Institute of Biochemistry of the Romanian Academy, 296 Splaiul Independentei, 060031, Bucharest, Romania

Resume : Lead-free (Ba1−xCax)(ZryTi1−y)O3 (BCZT) materials have attracted attention in the last years for replacing piezoelectrics containing toxic elements in different applications. Recent scientific reports demonstrate the applicability of BCZT for biomedical applications. Laser based approaches to obtain BCZT as biomaterials which supports cellular adhesion, proliferation and differentiation, can have important impact to their exploitation in a variety of biomedical applications. The BCZT thin films have been obtained using Matrix Assisted Pulsed Laser Evaporation method. Starting from a frozen target containing BCZT nanopowders, thin films have been obtained on Pt-coated kapton substrates. The cell proliferation studies have been made using epithelial embryonic kidney HEK293 cells and malignant melanoma A375 cells, which were seeded onto BCZT biomaterial. The results suggest that BCZT material led to an increase proliferation level compared to borosilicate glass coverslips, irrespective of the cell line tested. The immunofluorescence study shows that the two cell lines used in our experiment adhere on BCTZ material and display normal morphology on both glass coverslip and BCTZ material.

Authors : A. Andrei, G. Stanciu, N. D. Scarisoreanu, R. Birjega, A. Bercea , V. Ion , M. Dinescu
Affiliations : National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania

Resume : Strontium barium niobate SrxBa1-xNb2O6 (0.25 ≤ x ≤ 0.75, SBN) is a ferroelectric solid solution with tetragonal tungsten bronze structure. SBN exhibits a large value of electro-optic (EO) coefficient, up to 400 pm/V, much higher than LiNbO3 (~ 31 pm/V). Doping strontium barium niobate with calcium (Ca) the electro-optic coefficient (r33) can be further improved. We report in this paper on the optical and electrical properties of epitaxial strontium barium niobate (SrxBa1-xNb2O6- SBN) and Ca- doped SBN thin films obtained by PLD and RF assisted PLD on different substrates. The microstructure, morphology and stoichiometry of the as obtained layers 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. A parametric study on the influence of Ca doping amount on the properties of the SBN thin layer was carried out. The maximum measured change of the refractive index was found to be Δn = -0.00846 for Ez=25 kV/cm and the calculated value of electro-optic coefficient was 40 pm/V.

Authors : Valentin ION, Nicu D. SCARISONEANU, Andreea ANDREI, Ruxandra BIRJEGA, Nicoleta L. DUMITRESCU, Maria DINESCU
Affiliations : National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania

Resume : The perovskitic materials with small band-gap are very attractive for photovoltaic and photocatalytic applications. Multiferroic bismuth ferrite (BiFeO3-BFO) is an inorganic compound with perovskite structure and a band gap value of Eg~2.7 eV. In this work, we report on the properties of BFO and Y doped BFO thin films deposited by pulsed laser deposition (PLD) on different substrates as Nb doped SrTiO3, GdScO3, ITO/SiO2. A parametric study on the influence of deposition parameters on the properties of the deposited layer was carried out. Crystallinity and topography of thin films surfaces were investigated by X-ray diffraction, Transmission electron microscopy (TEM) and Atomic force microscopy (AFM). The optical properties were determined by spectroscopic ellipsometry (SE) and the values of band gap (Eg) where calculated from Tauc plot. We demonstrated that doping bismuth ferrite with rare earth elements like Yttrium in different concentrations, the bad gap values can be tuned. Thus, 3, 5 and 10%Y doping results in a decrease of the band gap value from 2.7 eV to 1.9 eV.

Authors : J. Hulik 1,2, F. Le Normand 1, F. Antoni 1, W. Uhring 1, P. Veis 2
Affiliations : 1 ICube, MaCEPV, 23 rue du Loess, 67037 Strasbourg, France; 2 Comenius University, Faculty of Mathematics, Physics and Informatics, Department of Experimental Physics, Mlynská dolina F1, 84248 Bratislava, Slovakia

Resume : Diamond-like carbon (DLC) have been produced by pulsed-laser deposition (PLD) of highly-oriented pyrolytic graphite (HOPG) target on transparent substrates, like quartz or glass, in order to use DLC as a buffer layer to obtain graphene-like films on top of the multilayer structure of DLC by thermal annealing process performed in Ultra High Vacuum (UHV) chamber using temperatures as high as 1373 K. The process of DLC production by PLD has been investigated using several techniques. The plasma dynamics have been studied by the Camille iCCD camera by Photonetics equipped with internal filter wheel using several optical filters and different time delays. The optical emission spectroscopy (OES) has been used for the spectral analysis of the plasma and the determination of the plasma parameters under different deposition conditions (e.g. laser fluence, laser wavelength). The Andor Mechelle ME 5000 OES spectrometer equipped with iCCD camera Andor iStar has been used for this purpose.

Authors : Frédéric Dumas-Bouchiat1, Catalin Constantinescu1, Thibaut Devillers2,3, Corinne Champeaux1, Dominique Givord2,3, Nora Mary Dempsey2,3
Affiliations : 1Univ. Limoges, CNRS, ENSCI, SPCTS, UMR 7315, F-87000 Limoges, France. 2Univ Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France 3CNRS, Inst NEEL, F-38042 Grenoble, France

Resume : Downscaling dimensions is favourable to magnetism. The synthesis of micro-magnets with high performances is conditioned to two essentials points: (i) keeping intrinsic micro-magnetic material properties close to the best macroscopic magnet (remanence & coercivity); (ii) increasing the magnetic field gradient (up & down close micro-magnets produce huge magnetic fluctuations in space). For this, high quality hard magnetic films (NdFeB, SmCo, FePt) were realized and optimized thanks to a triode sputtering process. Using pulsed laser-based approaches, a first method (Thermo-Magnetic Patterning, TMP1) was developed using heat diffusion through hard magnetic materials. Laser irradiation allows designing arrays of high performance micro-magnets of about 10 to 100 µm in size producing stray magnetic field gradients up to 106 T/m in the magnet's vicinity. Following TMP principles and as a derivative method, recent developments of specific masks using a collection of small UV-transparent spheres as lens deposited by a Langmuir-Blodgett process, has allowed the realization of compact array of very small magnets (around µm). All these developments will be presented and several applications based on magnetic forces and magnetic traps (2, 3) will be discussed. [1] Dumas-Bouchiat, APL 96 (2010) [2] Zanini, APL 99 (2011) [3] Brunet, Nat. Comm. 4 (2013)

Authors : N. E. Stankova, P. A. Atanasov, At. N. Tzonev, A. Perrone, A. Kapoor
Affiliations : Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Blvd., Sofia 1784, Bulgaria, Department of Solid State Physics and Microelectronics, Faculty of Physics, University of Sofia, 5 J. Bouchier Blvd., Sofia, Bulgaria, National Institute of Nuclear Physics and University of Salento, Department of Mathematics and Physics “E. De Giorgi”, 73100 Lecce, Italy, Department of Electronic Science, University of Delhi South Campus, New Delhi - 110021, India

Resume : Noble metal (Au, Pd)/TiO2 core-shell or sandwich nanostructures are obtained by using two fabrication methods: pulsed laser deposition (PLD) and pulsed laser nanostructuring (PLN). The laser nanostructuring is performed in order to modify the morphology of the as-deposited nanostructures and hence to change their optical properties. Titania coating caused shift of the Localized Surface Plasmon Resonance (LSPR) band of the metal nanoparticles toward the longer wavelength side. The characterization of the metal/TiO2 nanocomposites consists of different parameters like: the weight ratio of metal to TiO2; the arrangements, the thickness and the sizes of the metal core and TiO2 shell in nanostructured systems; the light absorption, scattering and LSPR capacities of such nanoobjects as well. Change of the experimental parameters enables successful control of these features and tuning of the LSPR across the visible spectrum. The morphological, structural and optical properties are studied by using field emission scanning electron microscopy (FESEM), energy-dispersive x-ray (EDX) and UV–vis spectroscopy. It is hoped that our work could render guided information for steering toward the design and application of TiO2-coated core–shell nanomaterials with tunable plasmon absorption shifted to the longer (visible) wavelength side for further efficiency improvements of the plasmonic solar cells.

Authors : A. Vlad1, R. Birjega1, A. Matei1, V.Ion1, I. Tirca1#, M.Dumitru1, D. Popescu1, M. Dinescu1, R. Zavoianu2, O.D.Pavel2 , M.C.Corobea 3
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, Bucharest, Romania #University of Craiova, Faculty of Sciences, RO-200585, Craiova, Romania

Resume : The aim of this work was to produce organic-nanohybrid thin films of photofunctional guest intercalated in layered double hydroxide host via pulsed laser deposition (PLD). Mg-Al layered double hydroxides (Mg/Al-LDHs) thin films with organic chromophores intercalated in the structure of LDH were deposited. The MgAl-LDH powder was prepared using co-precipitation method. Commercial dye coumarin 343 and food colorant curcumin were used as organic chromophores. The X-Ray Diffraction (XRD) and Fourier Transform Infra-Red Spectroscopy (FTIR) show the intercalation of chromophores into the LDH interlayer. A comparative study of the UV absorption ability of the chromophores modified LDH nanocomposites, and the effect of intercalation on the morphology and optical properties are evidenced. The films were deposited using a Nd:YAG laser working at different wavelength (266 nm, 532 nm and 1064 nm) having a 10 Hz repetition rate.

Authors : L.N.Dumitrescu1,2, I.Tirca1,2, V.Ion1, A. Moldovan1, V.Marascu1,3, V.Dinca1, M. Dinescu1
Affiliations : 1National Institute for Laser, Plasma and Radiation Physics, Atomistilor, Magurele, Bucharest, Romania; 2University of Craiova, Faculty of Sciences, Craiova, Romania; 3University of Bucharest, Faculty of Physics, Bucharest, Romania;

Resume : Polyvinylidene fluoride (PVDF) is a very attractive polymer for a wide area of applications in electronics and biomedical sciences due to its properties as polymorphism, heat resistance and piezoelectric behaviour [1]. In this work, we present preliminary results on optical, morphological and chemical properties correlated with deposition characteristics of PVDF coatings obtained by laser technique (matrix assisted pulsed laser evaporation (MAPLE)). A 266 nm laser wavelength with a repetition rate of 10 Hz was used to ablate a frozen target with different concentrations of PVDF in di-methyl sulfoxide (DMSO) organic matrix solvent. Different substrates were used as collecting surfaces (Si, SiO2). The laser fluence (0.3-1.1 J/cm2), target concentration (0.5-7%) and number of pulses were correlated to the deposition characteristics for achieving optimal uniform and functional thin films The optical, morphology and chemical structure properties of the resulted coatings were investigated by ultraviolet visible spectroscopy (UV-VIS), spectroellipsometry (SE), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). Based on the achieved results, we demonstrate that MAPLE is an adequate method for obtaining PVDF thin films with optical and chemical structure characteristics similar with control thin films and in agreement with the literature [2]. Acknowledgement: This work was supported by Romanian National Authority for Scientific Research (CNCS – UEFISCDI), under the projects PNII- PT-PCCA-2013-4-199 and PN-II-RU-TE-2014-4-2434

Authors : Andrea Cazzaniga, Rebecca B. Ettlinger, Stela Canulescu, Nini Pryds, Jørgen Schou
Affiliations : Technical University of Denmark, Risø Campus, DK-4000 Roskilde, Denmark

Resume : Earth-abundant non-toxic materials Cu2SnS3 (CTS) and Cu2ZnSnS4 (CZTS) are very appealing for cheap, large-scale production of thin-film solar cells. Due to their complex stoichiometry it is very difficult to obtain a single phase material with standard methods, evaporation or sputtering deposition, but also with pulsed laser deposition (PLD). Here we discuss the fabrication of thin films of CTS and CZTS made with PLD (248 nm, KrF laser) from sintered targets in vacuum. Usually, e.g. in PLD of oxide materials, the loss of the most volatile component, i.e. oxygen, can be compensated with the introduction of a reactive background gas in the chamber, and in our case for sulfides with H2S in the chamber. H2S is explosive and toxic, so that the sulfur deficit in the film is usually compensated by annealing in a sulfur environment after deposition. However, the least volatile element, copper, is also not transferred as expected. The stoichiometry of the deposited films strongly depends on the laser fluence: severe deficit (up to complete lack) of copper in the film is observed when the fluence is below 0.4 J/cm2, while a copper rich composition is observed at fluence values above 1 J/cm2. The stoichiometry of the deposited films can be understood in terms of the volatility and cohesive energy of the atoms composing the target, which is very different among copper, zinc, tin and sulfur. A narrow range of fluence values that preserve the target stoichiometry for the metals is found.

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Organics, polymers and biomaterials : Douglas B. CHRISEY
Authors : V. Califano, F. Bloisi, A. Aronne, A. Costantini, R. Di Girolamo, C. De Rosa, F. Auriemma, L. Vicari
Affiliations : V. Califano: Istituto Motori CNR; F. Bloisi and L. Vicari: Department of Physics, Università degli Studi di Napoli Federico II and SPIN-CNR Napoli; A. Aronne and A. Costantini: Department of Chemical Engineering, Materials and Industrial Production, Università degli Studi di Napoli Federico II; R. Di Girolamo, C. De Rosa, F. Auriemma: Department of Chemical Science, Università degli Studi di Napoli Federico II.

Resume : Lignocellulosic bioethanol is a potential alternative biofuel. The raw material for its production is cellulose, which is renewable, abundant and inexpensive. The enzymatic hydrolysis of cellulose to obtain fermentable sugars is carried out by a complex of enzymes called cellulase. The synergistic action of these enzymes leads to cellulose hydrolysis. Exo-glucanases and endo-glucanases act on cellulose producing cellobiose and short-chain oligosaccharides, which are hydrolyzed by beta-glucosidases. Immobilizing enzymes on insoluble supports can address the high cost of enzymes by allowing reuse, continuous processing and enhanced stability. However, cellulose being insoluble can be an obstacle for the production of active immobilized cellulase. Actually, exo-glucanases and endo-glucanases must adsorb to the surface of cellulose to perform their action, which can be inhibited if they are in immobilized form. On the contrary, immobilization of beta-glucosidase can be advantageous since cellobiose is soluble. In this work the possibility to prepare beta-glucosidase biofilms by Matrix Assisted Pulsed Laser Evaporation (MAPLE) in which the enzyme preserves its structure is explored. Benefits of using MAPLE for enzyme immobilization include independence of polypeptide conformation on enzyme/support interaction and dry deposition allowing the use water-incompatible supports and multilayer deposition. The conformational analysis of the enzyme secondary structure, whose preservation is essential in order to retain the catalytic activity, is performed by FTIR, a well-known technique to study protein and polypeptide secondary structure. The morphology of the obtained film is analyzed by FESEM.

Authors : A. Bensalah-Ledoux, L. Guy, J. Penuelas, P. Renieri, B. Baguenard, C. Leluyer and S. Guy
Affiliations : Institut Lumière Matière, UMR CNRS ; Université de Lyon, CNRS- Université-Lyon 1, 69622 Villeurbanne Cedex, France Laboratoire de Chimie; École Normale Supérieure de Lyon, 46 Allée d’Italie, 69364 Lyon Institut des Nanotechnologies de Lyon, UMR CNRS 5270, École Centrale de Lyon 36, Avenue Guy de Collongue 69134 Ecully France

Resume : New chiroptical devices based on high optical activity (OA) thin films have recently attracted great interest because they lead to new optical polarizations propagation [1, 2] Organic materials made of high specific OA molecules are good candidates for such devices. Deposition of these materials requires techniques which are able to conserve the chirality and allow elliptically polarized light propagation. Pulsed Laser Deposition (PLD) has been mainly used for inorganic compounds. Nevertheless, since the 90’s, small organic molecules have been deposited with little thermal or photochemical damage [3-5]. Our group has succeeded in depositing high quality wave guiding thin films of amino acids [8], calix-arenes[9] and proteins[10]. More recently, we have investigated the PLD technique to grow thin films based on chiral bridged binaphtyls [11] and helicen-like molecules. We focused on the conservation of the chiroptical properties during the deposition process. We demonstrated that, by finely tuning the deposition conditions, it is possible to transfer the molecular chirality from the target to the thin film, and thus, to realize transparent thin films with high rotary power. Chiral HPLC and RMN analysis of the dissolved films reveal that all the molecules degrade at the same laser power threshold but that the racemization of the molecules is structure dependent: neither binaphtol and ether-bridged binapthyl nor helicen-like molecules undergo racemization under the degradation threshold. In situ Circular Dichroism (CD) spectra and (OA) measurements confirm these findings. In the case of bridged binaphtyls molecules, transparent, isotropic 2m thick films with OA of 15°/mm at 546nm were successfully deposited while for helicen-like molecules, even a higher OA is measured. However, during the deposition process, the helicen-like molecules self-assemble leading to anisotropy in the out of plane direction. Furthermore, estimation of the thermal load reveals that, due to its instantaneous nature, PLD does not induce thermal degradation; only photochemical processes are involved in racemization and degradation. These observations may lead to the general use of the PLD to grow chiral organic thin films. Refs: [1] V. I. Lindell, A. Shivola, S.A. Tretyakov, and AJ Viitanen. In Electromagnetic waves in Chiral and Bi-Isotropic Media, ed. Artech House, (1994). [2] N. Engheta and P. Pelet. Opt. Lett., 14(11):593–5, (1989). [3] E. Ina, N. Matsumoto, E. Shikada, F. Kannari, Appl. Surf. Sci. 5741: 27-129, (1998). [4] G.B. Blanchet, C.R. Fincher, and I. Majovich. J. Appl. Phys., 94:6181, (2003). [5] Y. Tsuboi, M. Goto, A. Itaya, J. Appl. Phys. 89 : 7917, (2001). [6] A. Gutierrez-Llorente, R. Perez-Casero, B. Pajot, J. Roussel, R. M. Defourneau, D. Defourneau, J. L. Fave, E. Million, J. Perrière, Appl. Phys. A 77 : 785, (2003). [7] A. Gutierrez-Llorente, G. Horowitz, R. Perez-Casero, J. Perrière, J. L. Fave, A. Yassar, C. Sant, Organic Electronics 5 : 29, (2004) [8] M.A. Hernandez-Perez, C. Garapon, C. Champeaux, and J.C. Orlianges. In 8th International Conference on Laser Ablation, pages 724–727, (2007). [9] M. A. Hernandez-Perez, C. Garapon, C. Champeaux, A. W. Coleman, P. Shahgaldian, J. Mugnier, Appl. Phys. A 79 : 1473, (2004). [10] A. Hernandez-Perez, C. Garapon, C. Champeaux, P. Shahgaldian, A.W. Coleman, J. Mugnier, Appl. Surf. Sci. 658 : 208-209, (2003). [11] S. Guy, L. Guy, A. Bensalah, A. Pereira, V. Grenard, O. Cosso,and T. Vautey, Journal of Material Chemistry 19: 7093, (2009).

Authors : Miroslav Jelínek1,2, Tomáš Kocourek1,2, Jan Remsa1,2, Jan Mikšovský1,2, Petr Písařík 1,2,
Affiliations : 1. Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8, Czech Republic 2. Czech Technical University in Prague, Faculty of Biomedical Engineering, nam. Sitna 3105, 27201 Kladno, Czech Republic

Resume : In this contribution we concentrate on fabrication of doped biocompatible thin films by using hybrid laser- based deposition technologies in : a) arrangement with two beams of simultaneously running two lasers focused on two different targets (matrix target material and dopand material) (Fig.1a.), b) arrangement with simultaneously running PLD and magnetron (Fig.1b.). Fig.1. Laser based hybrid deposition arrangements (a- using two lasers, double PLD, b) using laser magnetron, PLDMS) In the case of double beam pulsed laser deposition (PLD PLD) technology, two independent pulsed fluxes of high energetic particles (up to 1 keV) intersect on the substrate. In arrangement combining PLD with magnetron sputtering (PLDMS) the growing layer consists from low energetic particles continuously sputtered by magnetron (~ 5 eV) and pulsed flux of high energetic material ablated by PLD. Both fluxes are directed to the substrate. The two different hybrid technologies, based on different physical principles and kinetic energy of particles, result in creation of layers of different properties even for the same concentration of dopands in matrix (film). It is supposed that for higher deposited plasma energies, the increase of film densification is reached. Hybrid based laser technologies make possible the easy fabrication of nanocrystalline, doped, nanocomposite and gradient layers by changing of parameters of material fluxes and deposition conditions. In our contribution we present details of both laser- based hybrid technologies and compare properties of created doped biocompatible layers. By changing deposition conditions the films of large scale of dopand concentrations (from zero to 25 at.%) were prepared. The focus was on titanium, chromium and silver doped diamond like carbon (DLC) layers. Experiences with experimental arrangements and comparison of results of physical, mechanical and biomedical properties of doped DLC layers will be presented and discussed. Acknowledgment: The project has been supported by Czech Grant Agency under GA15-05864S.

Authors : M. Novotny(a), E. Maresova(a), J. Bulir(a), J.Sebera(a), M. Vondracek(a), P. Hubik(a), J. Lancok(a), P. Fitl(b), J. Vlcek(b), M. Vrnata(b), A. Bensalah-Ledoux(c), S. Guy(c), R. Slota(d)
Affiliations : (a) Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague, Czech Republic (b) University of Chemistry and Technology, Technicka 5, 166 28 Prague 6, Czech Republic (c) Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France (d) Faculty of Chemistry, Opole University, ul. Oleska 48, 45-052 Opole, Poland

Resume : Phthalocyanines (Pcs) exhibit unique properties, i.e. semiconductivity, photoconductivity, chemical stability and optical absorption in the UV-VIS region. These properties make the Pcs suitable candidates for optoelectronic devices, small molecular organic solar cells or chemiresistive gas sensors. Metal ’mono’-Pc compounds, i.e. ZnPcs, CuPcs, are most commonly utilized. Lanthanide bis-phthalocyanines (LnPc2) based on two macrocycles coordinated by the rare earth metal offer additional possibilities. Phthalocyanine thin films (ZnPc and GdPc2) were grown by Pulsed Laser Deposition (PLD) using KrF laser in vacuum on fused silica and Si substrates at room temperature. The effect of laser fluence (in the region from 10 mJ/cm2 to 100 mJ/cm2) and repetition rate (up to 200 Hz) on the Pcs' film growth and properties was investigated. The growth of Pcs' thin films was in-situ monitored using transmission measurement in the UV-VIS spectral range. The optical properties were characterised by spectrophotometry and spectral ellipsometry. The electrotransport properties were analysed by van der Pauw method. Electronic structure was analysed by XPS. Morphology was studied by SEM and AFM. The deterioration of the films was examined by FTIR. DFT/TD-DFT calculations aided to correlate the optical properties and molecular arrangement. The properties of PLD and organic molecular evaporated films were compared. We demonstrated PLD may be considered as a successful technique for fabrication of Pcs thin films.

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New sources, industrial trends, large-area PLD : Eric MILLON
Authors : Rik Groenen, Cas Damen, Gertjan Koster, Guus Rijnders
Affiliations : Twente Solid State Technology B.V.; MESA+ Institute for Nanotechnology, University of Twente, The Netherlands

Resume : TSST has developed an Pulsed Laser Deposition (PLD) system with which buffer and functional layer growth on 4” silicon wafers is investigated and optimized. We present the results from this system on the growth of La0.67Sr0.33MnO3 (LSMO) thin films on YsZ//CeO2//SrRuO3 buffer layers on 4'' silicon wafers. Film quality is investigated with X-Ray Diffraction and magnetic characterization. Rocking curve measurements around the LSMO (002) Bragg reflection show values of ~1degree, which is comparable to the quality of films grown in typical <1” small scale experiments. A striking growth temperature dependence in the crystallinity of LSMO is shown. With the introduction of the SRO layer LSMO films show single phase crystallinity and magnetic properties for temperatures as low as 250C. When this SRO layer is lacking, fully amorphous film growth is observed at higher temperatures up to 550C. We suggest that the occurrence of this LSMO high quality crystal growth at these remarkable low growth temperatures can be understood by an improved surface diffusion induced by the B-side to A-side termination switch introduced by the SRO buffer layer. This is necessary to promote species intermixing on the surface to obtain preferential phase nucleation and overcome nucleation of various phases. Unlike small scale experiments, the PLD plume is scanned and fully collected on the wafer, where recent experiments have shown the temporal and spatial dependence of the composition of the plasma plume.

Authors : N. Hildenbrand, J.M. Dekkers, A. Janssens
Affiliations : Solmates BV, Drienerlolaan 5 (building 46), 7522 NB, Enschede, The Netherlands

Resume : It is well known that Pulsed Laser Deposition (PLD) is a very flexible and versatile technique allowing fast optimization of new and complex material thin films. 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 Solmates PLD 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. Thanks to those characteristics, integrating PLD thin films on devices becomes relevant for (pilot) production and commercialization. In this contribution the latest performance and specifications of Solmates PLD platform are addressed. Data on stability and reproducibility of wafer scale deposition of PZT thin films with excellent properties will be presented. Furthermore, two qualified processes Indium Tin Oxide and Aluminum Oxide thin films will be used to show some key capabilities of PLD such as damage free deposition on organic electronics or control of thin films density and microstructure for optical or sensing applications.

Authors : M. Nistor
Affiliations : National Institute for Lasers, Plasma and Radiation Physics (NILPRP), Plasma Physics and Nuclear Fusion Laboratory, L 22, Str. Atomistilor 409, P.O. Box. MG-36, 77125 Bucharest-Magurele, Romania

Resume : Pulsed electron beam deposition (PED) is an emerging thin film growth method which uses a pulsed electron beam (110 ns pulse width and electron energies distributed up to 16 keV) to ablate a target material. The ablation processes in PED and PED are schematically similar due to the pulsed nature of the processes: a very anisotropic character of the ablation plume and a high energy of the emitted species. The use of electron instead photon-matter interaction leads to an extension of the range of materials that could be ablated, e.g. to those that are transparent to laser wavelengths used in PLD. We have designed and developed a PED set-up for thin film growth with specific relationship between the discharge parameters, electron beam energy, plume dynamics and their influence on film properties. Thin films of complex materials, whatever their composition or properties, have been obtained by PED. Epitaxial thin films have been obtained starting from relatively low temperatures and the tuning of the physical properties of thin films was possible by the precise control of the growth conditions. Physical properties of oxide thin films grown by PED will be compared with those observed for PLD method, evidencing the differences and specificities of each method for the thin film growth.

Authors : P. Pira, J. Lancok, T. Burian, J. Wild, J. Bulir, L. Juha, K. Kolacek, Z. Zelinger, V. Nevrly, J.J.Rocca
Affiliations : Institute of Physics ASCR, Prague, Czech Republic; Faculty of Mathematics and Physics, Charles University in Prague, Prague, Czech Republic; Institute of Plasma Physics ASCR, Prague, Czech Republic; J. Heyrovský Institute of Physical Chemistry ASCR, Prague, Czech Republic; 5 VŠB-Technical University of Ostrava, Ostrava-Poruba, Czech Republic; Colorado State University, Fort Collins, CO, USA

Resume : Interaction of extreme ultraviolet radiation (XUV; 10 nm < λ < 100 nm) with matter differs dramatically from that of the long-wavelength radiation (UV-Vis-NIR). The interaction of the short wavelength radiation occurs mostly due to the photo-effect in atoms of the irradiated material. In addition to that, the XUV radiation is not back-reflected by solids and plasmas under the normal incidence conditions. A PLD (pulsed laser deposition) technique based on a suitable XUV laser can benefit from these two facts. Capillary-discharge XUV laser (XUV CDL) systems of two different constructions were used in this study, both lasing on neon-like argon ions emitting laser radiation at 46.9-nm wavelength delivered in nanosecond pulses. The XUV-CDL devices deliver beams of 26.4-eV photons with an average energy of  0.001 and 0.01 mJ/pulse; the beam is focused inside a vacuum chamber by a spherical multilayer Sc/Si mirror reaching in the focus a fluence level of  100 mJ/cm2 and  1 J/cm2 on the target surface, respectively. XUV-laser-produced plasma plumes were characterized by Langmuir probes, various imaging techniques and mass spectroscopy. Irradiated samples were investigated by Nomarski (DIC) microscopy and SEM, AFM, and WLI profilers. The ablation rate was determined from the AFM/WLI measured maximum depth of the crater created by a single XUV-laser pulse. The measured ablation threshold was compared to that calculated by means of XUV ABLATOR computer code. Results of our experiments dealing with the XUV-CDL-induced ablation/desorption of ionic crystal (i.e., fluorides: LiF, CaF2, and LaF3 and iodides: CsI and PbI2) and metals (e.g., Ag and Bi) will be presented and discussed.


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Symposium organizers
Eric MILLONUniversité d'Orléans – CNRS

GREMI, 14 rue d'Issoudun, 45067 Orleans Cedex 2, France
Maryline GUILLOUX-VIRYUniversity of Rennes 1

Institut des Sciences Chimiques, Solid State Chemistry and Materials Group, Bat 10A, Campus de Beaulieu, 35042 Rennes Cedex, France
Petar ATANASOVBulgarian Academy of Sciences (BAS)

72 Tsarigradsko Shose Blvd, Sofia 1784, Bulgaria
Thomas LIPPERTPaul Scherrer Institut

OFLB U110, CH-5232 Villigen PSI, Switzerland