Table of contents

The International Summer School on Vacuum, Electron and Ion Technologies (VEIT) has been organized biennially since 1977 when the series of VEIT Schools was launched by the Institute of Electronics, Bulgarian Academy of Sciences with the aim to act as a forum for interchange and dissemination of knowledge and ideas on the latest developments in electron-, ion-, and plasma-assisted technologies. Beginning from 2001, the school has been jointly organized with the Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, Germany. Whereas, the school initially provided a meeting place for researchers mainly from Eastern and Central European countries, its importance grew issue by issue. The school is now a major scientific event and a meeting place for young scientists from Eastern and Western Europe involved in research and development associated with high-tech industries. Many former school participants have gone on to become leading scientists in research establishments and companies throughout the world. Leading international companies, such as High Voltage Engineering, Balzers, Varian, and Hauzer have used the VEIT forum to present their products through oral presentations, poster contributions or exhibits. The School Proceedings have been published in special issues of the international journals Vacuum, Plasma Processes and Polymers, Journal of Physics: Conference Series.

The Sixteenth VEIT school was held in the Black Sea resort Sunny Beach, Bulgaria on 28 September to 2 October 2009. It was attended by close to 110 participants from 13 countries: Belgium, Bulgaria, Czech Republic, France, Germany, The Netherlands, Romania, Slovak Republic, Spain, Sweden, Ukraine, UK and USA.

Following the tradition of publishing the VEIT Proceedings, a selection of papers presented at the event is published in this volume of Journal of Physics: Conference Series, under the originality and quality criteria of acceptance by the journal, including peer reviewing.

The school comprised nine oral and three poster sessions. Seventeen invited talks of general interest and six progress reports were presented orally. In total 63 contributed papers were presented during the poster sessions. There were several scientific highlights covering fundamentals of interaction of fast particles with solids and challenging practical applications ranging from novel techniques for creating hard coatings, optical/protective layers, biocompatible materials to nanosized structures produced by evaporation, sputtering or external irradiation. Latest results were presented on ion-beam synthesis and modification in both low-energy (deposition and film growth) and high-energy (sputtering, implantation) regimes, and processing of solid materials aiming at patterning the surface or to create nanophase systems towards for electronic or tribological/wear resistant applications.

Despite the busy scientific program, the atmosphere was relaxed and informal. The early afternoons of most conference days were free to stimulate both scientific and social interaction between participants, which often took place on the beach. The social program included a welcome reception, a conference banquet, and an outing to historical landmarks in Bulgaria.

VEIT 2009 owes its success to many people. The International Advisory Committee shaped the scientific program and ensured high-quality plenary presentations by careful selection of invited speakers. The Local Committee bore the brunt of the organization both at the conference site and in dealing with correspondence, abstracts, and manuscripts for these proceedings. We are grateful to our sponsors Forschungszentrum Dresden-Rossendorf, Dresden, Germany and Bulgarian Academy of Sciences, Sofia, Bulgaria for their generosity that enabled us to support the attendance of students and provided support to deal with mailing, printing, renting the conference site, etc. We would like to thank also all authors for their valuable contributions to these proceedings and to the school, as well as all reviewers for their important work.

The next conference in the series will be held in September 2011.

Wolfhard Möller, Nikolay Guerassimov, Chavdar Ghelev Guest Editors

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The study presents experiments on the determination of the electronegativity and its axial variation in an inductively driven hydrogen discharge, performed by using the laser photodetachment technique. The results showing high electronegativity with nonmonotonic axial variations and a maximum next to the rf power deposition region provide an experimental indication that a design of an efficient source of negative hydrogen ions based on a single-chamber discharge might be possible.

Based on a two-dimensional (2D) fluid-plasma model of low-pressure hydrogen discharges sustained by rf power deposition of the type of inductive discharges with a planar coil, the study presents the spatial distribution of the plasma parameters and of the fluxes in the discharge and discussions outlining plasma maintenance in regions outside the rf power input.

Based on a three-dimensional model developed within the fluid-plasma theory, the study presents results on the spatial structure of hydrogen discharges in the magnetic filter region of tandem plasma sources and an analysis on its formation by transport processes – particle and electron-energy fluxes – both across and along the magnetic field.

Thermal conductivities of binary gas systems are calculated on the basis of 12-6 Lennard-Jones and rigid sphere inter-atomic interaction approximations for the case of gas discharges in He and Ne with small admixtures of copper, bromine, hydrogen and strontium. Assuming that the gas temperature varies only in the radial direction and using the calculated thermal conductivities, analytical solutions of the steady-state heat conduction equation are found for two cases of uniform and non-uniform power input, respectively. For both cases the average gas temperature is found by averaging the radial gas temperature distribution over the radius. Measurement of the relative intensities of some He and Ne spectral lines originating from different upper levels has enabled us to determine the average electron temperature.

A new type of electric discharge was observed during studies of a DC discharge of the point-to-point type in air at atmospheric pressure. Some of its properties were studied with respect to its bactericidal properties.

The point-to-plane DC corona discharge in air at atmospheric pressure was stabilized by a serially connected ballast impedance. The ballast impedance was implemented by a resistor-capacitor group connected in parallel. In the case of connecting the serial impedance into the electric circuit of a negative corona, the transition into a spark takes place at parameters similar to those of a non-stabilized discharge. In contrast, in the case of a positive corona, the discharge does not undergo a transition into a spark, but rather into a mode of periodic streamers. We measured the bactericidal effect of the stabilized discharge. The experiments showed that after a 2-minute exposure the quantity of surviving bacteria decreased from 95% for a non-stabilized discharge down to 5% for a stabilized one.

A new long-life DC arc T-plasma torch [1] was studied. The well-known method of electric field strength measurements in a stabilized arc channel [2] was applied in a modified form as a consequence of the specific shape of the presumably diffuse anode spot attached to a gas vortex on the external surface of the anode unit. The electric field strength was determined assuming that the potential drop across the diffuse anode spot in the new plasma torch was small. This yielded a mean argon plasma conductivity σ ≤ 118 Ohm⁻¹ cm⁻¹ for arc current I ≤ 180 A which agrees with the independent experiment [2] thus affirming the correctness of the above assumption. The analysis of the known experimental and theoretical data on atmospheric argon plasma conductivity resulted in the selection of R.S. Devoto's theoretical dependence σ(T) [3] as the most reliable one for T = 800 − 20000 K at P = 1 atm, which allowed us to evaluate the mean argon plasma temperature at the exit of the plasma torch, namely, T ≤ 19 500 K.

Test results are presented for different configurations of newly developed optical sensors consisting of several narrow-collimated photo detectors pointed at a plasma jet along different directions in its cross section. The sensors are capable of detecting time-variations of the position, width and asymmetry of a plasma jet. Two plasma torches with different plasma forming gas, air and argon/water vapor mixture, were used in our experiments under typical atmospheric plasma spraying (APS) conditions. The tests are based on fast, side-on imaging of the plasma jet from two or three angles (viewpoints). Reference values for the jet center coordinates, width and maximum brightness were deduced by processing the full information in the images. Next, data from small areas were processed to obtain values of the same parameters that simulate the sensor actual performance. It is commented that the accuracy of the new sensors seems reasonable for the purpose of on-line control of APS.

This communication presents an algorithm for reconstructing the 3D distribution of optical radiation from a plasma object of irregular shape. The object is seen by a camera at three different angles. The photo density profiles in each single line of the three images are presented as sums of Gaussians; the reconstruction is made by means of a set of equations that relate radiation intensity in a 2D mesh to the Gaussian amplitudes. An example based on photographs of a typical plasma jet used for atmospheric plasma spraying is worked out.

The effect was investigated of nitrogen and ammonia plasma treatment of monocrystalline Si wafers. The experiments were carried out in a plasma-enhanced chemical vapor deposition reactor. The wafers were subjected to N₂ and NH₃ plasma treatment for varying times at temperature of 380 °C. The plasma treated surfaces were studied by transmission electron microscopy with C-Pt replicas, reflection high-energy electron diffraction and Auger electron spectroscopy. The results point to the growth of an amorphous layer on the surface. The Auger electron spectroscopy depth profiles obtained by sputtering show the presence of an oxynitride layer with varying composition depending on the time of plasma treatment. The Auger electron spectroscopy analysis shows that after 60 s of treatment in N₂ plasma, the nitrogen content is 8 at.%, while after 300 s it is 22 at.%, the thickness of the oxynitride nanolayer being 2.5-7.2 nm. In the case of NH₃ plasma the thickness calculated from the sputtering time (from 50 s to 15 min) varies between 2 and 12 nm, and the nitrogen content, between 5 and 35 at.%.

Fluorocarbon plasmas (pure and mixtures with Ar) were used to investigate the changes in the etching rate depending on the chalcogenide glasses composition and light exposure. The experiments were performed on modified commercial HZM-4 vacuum equipment in a diode electrode configuration. The surface microstructure of thin chalcogenide layers and its change after etching in CCl₂F₂ and CF₄ plasmas were studied by SEM. The dependence of the composition of As-S-Ge, As-Se and multicomponent Ge-Se-Sb-Ag-I layers on the etching rate was discussed. The selective etching of some glasses observed after light exposure opens opportunities for deep structure processing applications.

We studied the applicability of the spherically-symmetric (n-6) Lennard-Jones temperature dependent potential (LJTDP) for describing the binary interactions between O₂ molecules in the temperature range between 200 K and 1300 K for pressures below 0.1 MPa. We observed a reasonable agreement between the thermophysical properties calculated using the (n-6) LJTDP (second virial, viscosity, and diffusion coefficients) and the corresponding measurements. A similar good agreement is also observed between our results and other correlations given in the literature.

The structural properties were studied of poly-Si films prepared by aluminium induced crystallization (AIC) of amorphous Si films (a-Si:H) deposited on glass substrates covered with Al layer. Raman and XRD spectroscopy were used for characterization of their short and long range order, respectively. The UV-reflectance spectra of poly-Si films were measured as well, and their surface morphology was observed by optical microscopy. The dependence was revealed of the structural and optical properties of the poly-Si films obtained on the annealing gas atmosphere and the hydrogen pressure during the deposition of the a-Si:H precursor, together with the correlation between them. The poly-Si films were applied in p-poly-Si/n-ZnO heterostructures; the I-V characteristics of the latter are presented and discussed.

The epitaxial growth was compared of cubic silicon carbide on 6H-SiC substrates prepared in four different ways: (i) as received, (ii) re-polished, (iii) annealed and subsequently covered by a Si layer, (iv) with a (111) 3C-SiC buffer layer. The morphological details of the grown layers were studied by optical microscopy and their structure, by transmission electron microscopy. The influence of the substrate on the nucleation of 3C-SiC, on the homoepitaxial 6H-SiC nucleation before 3C-SiC and on the defect formation, primarily twinning, is discussed.

La_0.7Sr_0.3MnO₃ (LSMO) films with different thickness were deposited directly on r-cut sapphire substrates by RF off-axis single magnetron sputtering with a view to produce a suitable buffer for growing HTS YBa₂Cu₃O_7-δ (YBCO) films on top. These LSMO layers were polycrystalline and showed a ferromagnetic behavior at room temperatures. The top YBCO films were sputtered in a DC off-axis double magnetron system. The polycrystalline structures thus produced were characterized and discussed.

Dilute III-nitrides, such as GaAsN and GaInAsN, are of considerable current interest both from a fundamental point of view and for applications in solar cells, GaAs-based long-wavelength photodetectors and diode lasers. The addition of nitrogen leads to material properties that deviate strongly from those expected for conventional III-V solid solutions.

The possibility was investigated to use liquid phase epitaxy to incorporate nitrogen in epitaxial GaAsN/GaAs and GaInAsN/GaAs heterostructures. The structures were grown from Ga- and Ga-In- melts containing powder GaN as a nitrogen source. The initial growth temperature was varied in the range 560°C − 660°C. The low temperature growth favors nitrogen incorporation in the epilayers. The optical transmission and photoluminescence spectra of a set of structures grown at different temperatures were studied showing ternary and quaternary dilute nitride solid solutions with nitrogen content about 0.2 at.%. The photoluminescence spectra show emission from localized nitrogen states as well.

Solar photo-thermal collectors were prepared from pure diamond-like carbon (DLC) thin films on aluminum substrates. By only changing the deposition conditions (different bias voltage) of the DC PECVD process, coatings were fabricated consisting of five sublayers with the necessary optical parameters. As expected, absorption better then 0.9 was achieved already for submicrometer absorber thickness. Accelerated thermal ageing tests performed at 200°C and 300°C in air showed that the reflectance changes only slightly. Long operating life can, therefore, be expected of such absorbers.

Thin layers intended for gas sensors are prepared by vacuum co-evaporation of TeO₂ and Sn. The as-deposited layers consist of a nanosized oxide matrix and finely dispersed dopants (Te, Sn, TeO₂ or SnTe, depending on the atomic ratio R_Sn/Te). In order to improve the characteristics of the layers they are additionally doped with platinum. The gas sensing properties are strongly dependent on the atomic ratio R_Sn/Te, as well as on the structure, composition and surface morphology. The as-deposited layers with R_Sn/Te 0.8 are highly sensitive humidity sensors working at room temperature. Thermally treated Pt-doped layers with R_Sn/Te 2.3 are promising as ethanol sensors.

With the aim of obtaining more detailed knowledge about the surface morphology, structure and composition of layers sensitive to different environments, various techniques -TEM, SAED, SEM, EDS in SEM and white light interferometry (WLI), are applied. It is shown that all layers with 1.0 > R_Sn/Te > 2, as-deposited and thermally treated, exhibit a columnar structure and a very smooth surface along with the nanograined matrix. The thermal treatment causes changes in the structure and composition of the layers. The ethanol-sensitive layers consist of nanosized polycrystalline phases of SnO₂, Sn₂O₃, Sn₃O₄ and TeO₂. This knowledge could help us understand better the behaviour and govern the characteristics of layers obtained by co-evaporation of Sn and TeO₂.

The paper presents results on the synthesis of hard multilayer coatings consisting of titanium nitride and molybdenum nitride thin films with thickness of several nm. The TiN and Mo₂N films were successively deposited by reactive DC magnetron sputtering. These multilayer structures were investigated by Auger electron spectroscopy (AES), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), cross-section scanning electron microscopy (CSSEM) and cross-section electron probe microanalysis (CSEPMA). The mechanical properties of the multilayer coatings, namely, hardness, Young's modulus and the coefficient of plastic deformation were measured. The adhesion was evaluated by the Rockwell-C-impact test. Coatings with different total thickness were examined with respect to adhesion to substrates of tool materials.

This article reports the synthesis of wire structured ZnO by electrochemical deposition on a glass substrate covered by thin film of ITO or SnO₂ doped with F (SnO₂:F) and on a carbon tissue. The influence of the structure of the transparent conductive films on the structural properties of the ZnO films obtained was studied by SEM and Raman spectroscopy. The results show that the films have a columnar structure with grain size of about 200-500 nm. The films deposited on the SnO₂:F coated glass substrate have better structural properties. Pillar structure is observed on the surface of the fiber of the carbon tissue.

Eye-safety is of paramount importance in the use of laser-based instruments. Eye safe output at 1.54 micron is very important for various applications such as robot vision, range finding and laser radars in civil and military use. Nonlinear crystals have been used in state-of-the-art rangefinders for providing eye-safe output in the 1550 ± 50 nm band. We present our results on designing a back and a front mirror for eye-safe laser generation at a wavelength of 1538 nm. The back mirror is designed for high transmission at 1067 nm and high reflection at 1351 and 1538 nm. The front mirror is designed for high transmission at 1067 nm, high reflection at 1351 nm and partial reflection at 1538 nm. The optimized design is achieved using titanium dioxide and silicon dioxide layers. In the experiment, the coatings are fabricated by electron beam evaporation on BK7 glass substrates. The characteristics of the coated samples are compared with the results of the calculations, showing good correspondence. The laser mirrors so prepared passed the laser damage and durability tests.

In this work thin ZnO layers were grown by metal-organic PECVD (RF 13.56 MHz) on Si wafers. Zn acetylacetonate was used as a precursor and oxygen as oxidant. A system for dosed injection of the precursor and oxidant into the plasma reactor was developed. The influence of the substrate surface topology and temperature on the structural properties of the deposited layers was studied. ZnO and graphite powder dispersions were used to modify the silicon wafers before starting the deposition process of the layers. Some of the ZnO layers were deposited on the back, unpolished, side of Si wafers. Depositions at 400 °C were performed to examine the effect of the substrate temperatures on the layer growth. The film structure was examined by XRD and SEM. The results show that all layers are crystalline with hexagonal wurtzite structure. The crystallites are preferentially oriented along the c-axis direction perpendicular to the substrate surfaces. ZnO layers deposited on thin ZnO seed films and clean Si surface exhibit well-developed grain structures and more c-axis preferred phase with better crystal quality than that of the layers deposited on graphite seed layer or rough, unpolished Si wafer.

Results are presented on the deposition and characterization of thin SiO₂ and Al₂O₃ films containing Tb³⁺ ions developed for application as spectral converters. The films are prepared by RF magnetron co-sputtering. The photoluminescence (PL) is measured at room temperature using the 488 nm line of an Ar laser. The dependence is studied of the PL intensity on the Tb concentration in the film. It is found that the intensity exhibits a maximum at about 1 at.%. Annealing studies are performed on SiO₂:Tb using two different methods to improve the PL intensity. In both regimes of annealing, the best results are obtained at 650 − 700°C. After treatment at this temperature the Tb PL increases 2.5 − 3 times.

A comparative analysis is made of the parameters of oxide, nitride and multilayer coatings, such as TiN, deposited by means of Arc-PVD, oxide Al₂O₃ films deposited by magnetron sputtering (MS), and of multilayer TiN/Al₂O₃ on stainless steel (1H18N9) and a titanium-based material (Ti4Al6V). The corrosion examinations of anodic polarization by potentiodynamic method, Tafel and Stern curves and also impedance method at NaCl and SBF solutions were presented. The best corrosion resistance characteristics are exhibited by TiN/Al₂O₃ multilayer coatings on both stainless steel and titanium substrates.

The sorption properties with respect to gaseous NH₃ of e-beam evaporated TiO₂ layers were investigated by a quartz crystal microbalance (QCM) allowing the detection of nanograms of sorbed mass. The TiO₂ (249 nm thick) layers were deposited on 16 MHz resonators. The as-deposited TiO₂ layers were characterized by ellipsometry, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The measurements of the QCM-TiO₂ system's sorption properties were carried out on a laboratory setup allowing operation in dynamic and static modes under strict control of the process parameters which were recorded and processed automatically by an electronic measuring system. The sorption properties of TiO₂ were determined using the frequency shift (ΔF) of the QCM in NH₃ with concentrations ranging from 10 ppm to 1000 ppm. The time of sorption and de-sorption were defined; the maximal QCM frequency shifts for each NH₃ concentrations were measured and the sorbed masses were calculated. It was determined that ΔF increases from 8 Hz at 10 ppm to 216 Hz at 1000 ppm, which corresponds to sorbed masses of 2.78 ng and 75.19 ng, respectively. The results show that the QCM-TiO₂ system could very successfully be used as a sensor element for NH₃ detection in the range 10 – 1000 ppm.

We recently developed an approach to the estimation of the complex permittivity () and thickness (d) of very thin layers using measurements of their transmittance, front-side reflectance and back-side reflectance. The approach is based on a limited expansion of the Abelès characteristic matrix elements and is especially designed for characterization of very thin layers. In this paper we investigate the uncertainties of the estimated real part of (₁), the imaginary part of (₂) and d of semiconductor thin layers that are due to the methodological error and the experimental uncertainties in the optical quantities measured. It is shown that the effect of the uncertainties in the measurable quantities is significantly stronger than that of the methodical error and increases considerably with the decrease of the ratio d/λ (λ being the wavelength). An efficient two-step procedure is proposed to reduce this effect. First, we supply a criterion for determination of d with the lowest uncertainty from the ensemble of estimations constructed on a wavelength by wavelength basis. This is crucial for the next step: the estimation of ₁ and ₂. The approach proposed ensures estimation of ₁, ₂ and d with the highest accuracy, limited only by the methodological error.

Thin epitaxial La_0.67Sr_0.33MnO₃ (LSMO) films were deposited on single crystal MgO substrates. The electrical transport and magnetic properties of the films in the temperature range 4 – 350 K were investigated and strong correlation between them was registered. Magnetoresistance up to 52 % at temperature T = 256 K and magnetic field B = 5 T was achieved. The results obtained indicate that LSMO films with such properties are suitable for application as "barrier" layers in superconducting-ferromagnetic-superconducting heterostructures, but optimization of LSMO film thickness is needed.

The electrical properties of bilayer structures consisting of a superconducting (SC) and a ferromagnetic (FM) layer deposited on a LAO substrate were studied by a contactless technique in the temperature range from 77 K in the vicinity of the critical temperature. Two series of bilayers were investigated: – SC (YBCO) layers with thickness varying from 35 to 80 nm on a FM (LSMO) layer with a fixed thickness of 40 nm, and – a fixed-thickness YBCO layer (70 nm) on LSMO layers with thickness varying from 10 to 40 nm; YBCO layers deposited under the same conditions as reference. An interesting effect was observed, namely, when the temperature is reduced below the critical value, the bilayer inverts the magnetic field passing through it – the signal picked up by the receiving coil inverts its phase. The measurements of the critical current and temperature showed that when the YBCO layer is thicker than the LSMO layer, the latter acts as a buffer layer improving the SC performance. These is in contrast with the results published earlier by other authors on proximity effect and spin injection for bilayers and super lattices of SC/FM layers that are an order of magnitude thinner. The SC performance worsens only in the case when the YBCO and LSMO layers have a thickness of approximately 40 nm.

A summary is presented of the investigations on the key conditions ensuring electron-beam surface hardening of carbon steels. A numerical model is developed and used to calculate the temperature field caused by high frequency electron beam scanning. The numerical calculation results show that the heating and cooling rate depend weakly on the electron-beam power and are strongly influenced by the sample speed of motion, namely, they increase as this speed is increased. The efficiency of the process of electron-beam hardening of metals increases with the speed of motion of the samples treated.

A study was performed on the impact of the structure and properties of e-beam evaporated Ta₂O₅ films on the cell/material response. The surface properties and structure the films were investigated by means of XPS and XRD. The cyto toxicity and cyto compatibility were estimated by in vitro tests. Other parameters, such as the surface free energy (SFE) and fractional polarity, were determined by means of the Wu, and Owens-Wendt-Rabel-Kaelble methods. The dependence was followed of the cells adhesive behavior on the coatings surface composition and parameters. The best biological response parameters (total cell number, detached cells percentage, proliferation ratio) were obtained in the case of annealed Ta₂O₅ coatings with stoichiometric composition and the largest values of the SFE polar part and the of the fractional polarity.

Topography changes of a SiO₂ surface and formation of Si nanoclusters, induced by high-energy electron irradiation of ion implanted Si-SiO₂ structures, are studied by atomic force microscopy (AFM) measurements. Si ions with energy of 15 KeV and doses of 10¹² or 10¹⁶ cm⁻² are implanted in the Si-SiO₂ structures with an oxide thickness of 20 nm. The ion energy is chosen to produce maximum ion damage at the Si-SiO₂ interface. Some of the implanted samples are simultaneously irradiated by 20 MeV electrons with a flux of about 1×10¹⁵ cm⁻². AFM measurements indicated that the SiO₂ topography does not vary significantly only due to the ion-implantation. Si nanoclusters are observed in a SiO₂ layer after MeV electron irradiation. The measurements show that the size and shape of the Si nanoclusters depend significantly on the dose of the previously implanted ions.

In the present work, low energy ion beam irradiation was used for surface modification of polymethyl-methacrylate (PMMA) using silicon (Si⁺) as the ion species. After high doses ion implantation of Si+ in the polymer material, a characterization of the optical properties was performed using optical transmission measurements in the visible and near infra-red (IR) wavelength range. The optical absorption increase observed with the ion dose was attributed to ion beam induced structural changes in the modified material.

Visible photoluminescence (PL) of ion implanted polymers was studied. Different polymer materials were used for the purpose: polypropylene (PP), poly-tetrafluor-ethylene (Teflon), ultra-high-molecular-weight-polyethylene (UHMWPE) and UHMWPE+Bi. Ion implantation with Si⁺ and C⁺ was performed at energies of 30 keV with doses in the range 10¹³ – 10¹⁷ cm². The results show that a PL enhancement (PLE) effect may occur for some polymer materials if proper implantation energy and doses are employed, the effect in the case of some polymer materials implanted with Si⁺ and C⁺ being considerable. While the effect is observed for all doses of C⁺ implanted in UHMWPE, PLE is only observed for the lowest dose of Si⁺ (D = 1×10¹⁵ cm⁻²) implanted in Teflon, the further dose increase resulting in PL quenching only, presumably due to processes of structural degradation The appearance of ultra-violet (UV) range PL in the case of Si⁺ implanted UHMWPE could be originating from the formation of Si-related new defect sites, but more data are needed to explore this effect further into the deeper UV range (λ<350 nm).

A novel method was developed for physical deposition of thin polyimide layers by applying an argon plasma assisted process. The influence was investigated of the plasma on the combined molecular flux of the two thermally evaporated precursors – oxydianiline and pyromellitic dianhydride. The effects observed on the properties of the deposited films are explained with the increased energy of the precursor molecules resulting from the ion-molecular collisions. As could be expected, molecules with higher energy possess higher mobility and thus determine the modification of the films structure and their electrical properties.

We present results of our recent study on the heating process and near field localization arising when gold nanoparticles are irradiated by ultrashort laser pulses at wavelength of 800 nm. The system under consideration consists of Au nanoparticles with diameter of 40, 80, or 200 nm in vacuum or deposited on different substrates. Substrate materials with different dielectric properties are used in order to sense and visualize the nanoparticle heating and near field electromagnetic distribution. The theoretical analysis is based on the optical properties obtained by the Mie scattering theory. The absorption coefficients calculations are implemented in a two-temperature heat model for estimation of the nanoparticle temperature. The near field distribution in the vicinity of the particles is calculated by the finite difference time domain (FDTD) method. It is found that at even moderate laser fluences the temperature of the particle can reach a value sufficient for bubble formation in biological tissues. The analysis of the near field distribution shows that when the particle is deposited on a substrate surface, the dielectric properties of the substrate define the spatial distribution and the enhancement of the near field intensity. The observed localization and field enhancement may result in a precise modification of the substrate with a resolution defined only by the nanoparticle size. Such modifications are experimentally observed in different substrates.

A generalized non-local Fokker-Planck type kinetic equation obtained on the basis of quantum-mechanical formalism is used to study the conduction electron dynamics in model semiconductors excited by spatially inhomogeneous pulsed laser irradiation. In this approach the electrons are assumed to undergo a drift-diffusion motion in the energy-position manifold.

Thin films of AlN doped with Cr were formed on p-Si(100) substrates by pulsed laser deposition. Al-AlN:Cr-Si MIS structures were formed and their current-voltage and 1 MHz admittance characteristics were measured. The considerably smaller increase of the conductance at 300 K in comparison to that measured at 77 K is an evidence for tunneling type of conductance in these MIS structures. The current is limited by space charge at deep levels (traps) in these AlN:Cr films which determines the mechanism of the charge transport through the MIS structures. The density of the filled electron traps is in the order of 10¹⁶ cm⁻³.

Thin zinc oxide films (ZnO) were developed as a matrix-free platform for surface assisted laser desorption-ionization (SALDI) time-of-flight mass spectrometry. The ZnO films were deposited by RF magnetron sputtering of ZnO ceramic targets in Ar atmospheres on monocrystalline silicon. The generation under UV (355 nm) laser irradiation of positive ions of atenolol, reserpine and gramicidin S from the ZnO layers deposited was studied. All analytes tested were detected as protonated molecules with no or very structure-specific fragmentation. The mass spectra obtained showed low levels of chemical background noise. All ZnO films studied exhibited high stability and good reproducibility. The detection limits for test analytes are in the 10 femtomol range.

Mixed oxide films based on Mo and W were successfully prepared by atmospheric pressure CVD at the low substrate temperature of 200^oC. High amount of oxygen was used to ensure a high degree of oxidation resulting in more stoichiometric oxide films. The structural transformations under different thermal treatments were studied by Raman spectroscopy and FTIR spectroscopy analysis. The films were characterized electrochemically by cyclic voltammetry using different electrolytes, scan rates, etc. The mixed oxide films exhibited a strong electrochromic (EC) effect.

The photoinduced changes in the refractive index and optical band-gap of thin As₃₂S₃₄Se₃₄ films photodoped with silver were studied using spectrophotometric methods. The compositional profile of the films was revealed by means of Auger-electron spectroscopy.

A recently developed technique of modulated optical reflectance and its applicability to structural and defectoscopic analysis with high spatial resolution of the ferromagnetic LSMO materials is reported. The variation of the optical reflectance is measured within the active area in the laser focus on the surface of the thin film subjected to photothermal modulation. The measurement described is indicative of the magnetoelectric properties of the sample films and is found to be proportional to the thermal variations of the conductance and free carrier density.

This paper presents a practical non-destructive method for studying the film coating behavior of SAW devices by using a water soluble dielectric film (manitol) deposited on the SAW device surface by resistive evaporation. After measuring the electrical parameters of the film coated SAW device, the film can easily be removed from its surface by water rinsing without causing any damage to it. The SAW device can then be used over and over again in a large number of film depositions. The method was tested on a 1 GHz surface transverse wave (STW) resonator coated with manitol of varying thickness. After each coating and evaluation, the STW device was successfully recovered without significant performance degradation. Data is presented on the electrical changes of the STW device as a result of depositing manitol coatings of various thicknesses.

First principles calculations within the framework of the density functional theory with ultrasoft pseudopotentials and plane-wave wavefunctions basis set were performed to investigate the electronic and crystallographic structure of chromium nitride. Different types of antiferromagnetic orderings were considered in the calculations. Three crystallographic planes, namely {100}, {110} and {111}, most commonly observed during the growth process of CrN layers, were investigated assuming AFM1_[110] magnetic ordering. The corresponding surface energies and magnetic structures were simulated.

Superconductor-ferromagnet thin film heterostructures in lateral geometry were prepared to study the long-range proximity effect. The high temperature superconductor YBa₂Cu₃O_x (YBCO) as superconductive electrode and La_0.67Sr_0.33MnO₃ (LSMO) as ferromagnetic separation were used. The length of the ferromagnetic layer between two YBCO microstrip electrodes was about 3 μm. The temperature dependence of the resistance of these structures was measured. The results obtained showed that the separation of the superconducting YBCO microstrips is too large for observation of a long-range proximity effect; further optimization of the structures is, therefore, needed.

A double-layer structure of Al₂O₃ over ZrO₂ film is studied. Minimization of the average weighted reflectance is carried out to optimize the thickness of the two layers in the antireflection coating. An optimal value of 2.17% for the weighted average reflection is estimated. The optimal thicknesses of the layers are 49 nm for the bottom and 45 nm for the top layer. Low temperature spin coating technique is used to deposit ZrO₂ and Al₂O₃ films from sol gel solutions on polished silicon wafers, GaAs multilayer heterostructures and AlGaAs/GaAs solar cells. The density of the short-circuit photocurrent increases from 25 mA.cm⁻² for solar cells without an antireflection coating to 36 mA.cm⁻² for those with a double layer coating.