The transition metal oxides exhibit electrochromism, defined as color change caused by applied voltage. The electrochromic (EC) effect can be stronger in mixed oxides because of the higher optical absorption, due to electron transitions between two kinds of metal sites with different valences.Thin films Of MoO3 and mixed Mo/W oxides were obtained by atmospheric pressure chemical vapor deposition (CVD), using pyrolytic decomposition of metal hexacarbonyls. IR and Raman spectra are presented and compared with data for WO3 from previous investigation. Sputter auger spectroscopy was used to determine the chemical composition of the mixed films. The visible transmittance of films deposited on glass substrate was about 80%; on conductively coated glass (i.e. SnO2:Sb/glass) the visible transmittance drops to around 60%. After annealing, the optical transmittance of the single oxide films slightly improves, while for the mixed films it slightly decreases.The electrochromic properties Of MoO3 and mixed Mo/W oxide films were investigated by cyclic voltammetry performed in a conventional potentiostatic three-electrode configuration. Current and transmittance were measured simultaneously during the potential sweep at different wavelengths over the spectral range of 400-800 nm. Deep blue coloring of all the electrochromic films (MoO3, WO3 or Mo/WO3) appears only in the cathodic range, minimizing visible light transmittance. At positive potentials, the EC film starts bleaching (for about 3 min) and the film returns its initial transparency.It was found that the CVD deposited MoO3 and Mo0.07W0.93O3 thin films performed well as electrodes in electrochromic devices. We made devices based on Mo0.07W0.93O3/LiClO4 + propylene carbonate + polyvinyl alcohol + PVA/SnO2:Sb. The devices exhibited good cyclic reversibility (colored/bleached state) and good coloration efficiencies. We measured a transmittance change (600 nm) of 48.4% switching to 17.4% for our best device. (c) 2005 Published by Elsevier B.V.

The paper presents the recent study on the technology and investigation of thin metal oxide films based on transition metals, such as W and Mo. Defined is the application aspect of the research, by describing the optical systems based on these films, namely the electrochromic device and the X-ray mirror. Results on the optical absorption in the films are presented, and discussed by the specific structure of these materials. Electrochromic measurements of the MoO3, as well as of mixed oxide films based on W and Mo are more in details presented. A device based on mixed oxide films as working electrode is developed and its electrochromic functioning evidenced by the voltammograms, coloration efficiency and optical modulation is described.

Thin Films Of MoO3 and mixed Mo/W oxides were obtained by atmospheric pressure CVD, implying pyrolytic decomposition of metal hexacarbonyls. The optical transmittance was measured for the films. When deposited on typical glass substrates, the films showed about 80% transmittance in the visible. Oil conductive glass, this value dropped to around 60%. The electrochromic properties of MoO3 and the mixed Mo/W oxide films were investigated by cyclic voltammetry, performed in a standard three-electrode arrangement. The cyclic change of current and transmittance as a function of the applied voltage for different wavelengths was measured. Over the voltage range studied, coloring appears in the cathodic EC film - MoO3, WO3 or mixed film, which at negative voltage suddenly colors to deep blue. Correspondingly, at that moment, there is a minimum in the transmittance curve. Going towards positive applied voltages, the EC film begins bleaching (for about 3 minutes) and the cell regains its initial transparency. With the help of a monochromator, the experimental set-up allowed to study the change in the colour efficiency, as a function of different wavelengths in the spectral range of 400-800 nm.

Preface. Invited Papers. Large-Area Smart Glass and Integrated Photovoltaics C.M. Lampert. Photovoltaic Materials, an Overview of Historical Development, Current State of the Art and Future Scope D. Dimova-Malinovska. Electronic Characterisation and Modelling of Disordered Semiconductors J.M. Marshall. Measurement Methods for Photoactive Materials and Solar Cells G.S. Popkirov. Structural and Optical Properties of Microcrystalline Silicon for Solar Cell Applications R. Carius. Crystalline Silicon p-n Junction Solar Cells - Efficiency Limits and Low-Cost Fabrication Technology J. Szlufcik. Application of III-V Compounds in Solar Cells V.M. Andreev. Micro-/Poly-Crystalline Silicon Materials for Thin Film Photovoltaic Devices: Deposition Processes and Growth Mechanisms J.K. Rath. Micro-/Poly-Crystalline Silicon Materials for Thin Film Photovoltaic Devices: Physical Properties J.K. Rath. Micro-/Poly-Crystalline Silicon Materials for Thin Film Photovoltaic Devices: Application in Solar Cells J.K. Rath. Organic Materials and Devices for Photovoltaic Applications J.-M. Nunzi. Photovoltaic Applications M. Palfy. Past, Actual and Future EU-Funded Research, Technological Development and Demonstration Actions in the Field of Photovoltaics T.L. D'Estaintot. Contributed Papers. Evaluation of the Gap State Distribution in a-Si:H by SCLC Measurements A. Eray, G. Nobile. Creation and Annealing of Light Induced Metastable Defects in a-Si1-xCx:H A.O. Dodolbas, O. Oktu. Potential PV Materials Based on InN Polycrystalline Films: Growth, Structural and Optical Properties V.Ya. Malakhov. Light Soaking Effect in a-Si:H Based n-i-p and p-i-n Solar Cells G. Nobile, M. Morana. Accelerated Ageing Test of Solar Cells and Encapsulations V. Saly, et al. DifferentialSpectral Responsivity of c-Si:H Solar Cells M. Sendova-Vassileva, et al. Temperature and Compositional Dependence of Raman Scattering and Photoluminescence Emission in CuxGaySe2 Thin Films C. Xue, et al. Enhancement of the Photovoltaic Efficiency of Ge0.2Si0.8/Si Photodiodes M.M. Pociask, et al. Charge Carrier Transport and Photovoltage in Layers Based on Poly(3,3Phthalidylidene-4,4 Biphenylilene) A.R. Tameev, et al. Diagnostics of Large-Area Solar Cell Homogeneity by Local Irradiation V. Benda. Determination of Trap Parameters from Photocurrent Decay Measurements: Metal-Free Phthalocyanine Films I. Zhivkov, et al. Luminescent Properties of Li2GBP/YYGBP4O7 (LTB) Polycrystals at the Deviation from Stoichiometry B.M. Hunda, et al. Influence of Solution Resistivity and Postanodizing Treatment of PS Films on the Electrical and Optical Properties of Metal/Ps/Si Photodiodes K. Ait-Hamouda, et al. Study of Sol-Gel Derived Very Thin Films of Mixed Titanium Dioxide and Vanadium Oxide T. Ivanova, et al. Photoelectrochemical Characterization of Some Argyrodite-Type Materials Yu. Stasyuk, et al. Optical Absorption in APCVD Metal Oxide Thin Films K.A. Gesheva, et al. Extrinsic Surface Photovoltage Spectroscopy -- An Alternative Approach to Deep Level Characterisation in Semiconductors K. Germanova, et al. CELLO: An Advanced LBIC Measurement Technique for Solar Cell Local Characterisation J. Carstensen, et al. The Behaviour of PV Module Parameters as a Function of Solar Cell Temperature in Hot Climates P. Vitanov, et al. Application of SiO2: Re Layers for Improvement of the UV Sensitivity of a-Si:H Solar Cells M. Sendova-Vassileva, et al. Cost-Effective Porous Silicon Technology for Solar Cell Industrial

Mixed metal oxides based on MoO3 and WO3 are prepared by chemical vapor deposition (CVD) using a precursor-mixture Of MO(CO)(6) and W(CO)(6) powders. By pyrolytical decomposition of the mixed vapors at atmospheric pressure in presence of oxygen, thin films were deposited on silicon substrates at 200 degreesC. The films were characterized by Raman, IR and Ellipsometric Spectroscopies. In as-deposited form the films are amorphous as revealed by Raman spectra. Post-deposition annealing at 200 and 300 degreesC does not significantly change the vibrational and optical properties. Annealing at 400 and 500 degreesC leads to predominantly amorphous structure with appearing of crystalline phase. The character of the absorption spectra and the values of the optical energy bandgap (2.57-2.66 eV) suggest that the CVD-MoO3-WO3 oxide films have highly defective structure.

By chemical vapor deposition at atmospheric pressure using Mo(CO)6 precursor and Ar/O2 gas mixture, thin MoO3 films were prepared on Si substrates. The deposition and sublimator temperatures were in the range of 150–200 and 70–90°C, respectively. Investigations of the as-deposited MoO3 films were performed by spectroscopic ellipsometry (300–800 nm) and infrared spectrophotometry (200–1200 cm−1). The refractive index of the films was found to be in the range of 1.7–2.3 and the optical band gap energy, Eog, estimated from the absorption analysis, was in the range of 2.76–3.14 eV. The infrared spectra exhibit the characteristic peaks for β-modification of polycrystalline material.

Molybdenum oxide films were obtained at 200 degreesC by Chemical Vapor Deposition of Mo(CO)(6) at atmospheric pressure and at an optimal ratio of precursor vapors and oxygen. Vibrational and optical properties as dependent on process temperatures were investigated by Raman and Ellipsometric Spectroscopy. The as-deposited films are generally amorphous. A crystallization starts if films are heated at 200 degreesC up to 500 degreesC. Besides the basic Mo-O bands, after annealing a variety of additional vibrational bands was observed. This evidence for polycrystalline structure was also supported by the optical gap energy values found in the range of 2.72-3.63 eV typical for polycrystalline material.

Silicide formation due to thermal treatment of thin (200–1000Å) molybdenum films on single-crystal silicon substrates in the temperature range of 800–1000°C was studied. Rapid thermal annealing (RTA) in vacuum was performed on Mo/Si system to form silicides. Molybdenum films were deposited on Si (100) by chemical vapor deposition (CVD), using Mo(CO)6 (molybdenum hexacarbonyl) as precursor. The as-deposited films with thicknesses of 200 and 1000Å were heated in vacuum at RTA temperatures of 800 and 1000°C for time durations of 15 and 30s, 1 and 3min. The results from the X-ray diffraction analysis and the Reflection Infrared Spectroscopy measurements show that Mo films after annealing transform into Mo silicides, preferably tetragonal MoSi2 crystal phase. The presence of Mo5Si3 formation is also found. There is a change in the electrical resistance of the films before and after annealing. For the molybdenum silicides obtained the resistivity is in the range 0.9–9.8mΩcm.

This paper presents results on molybdenum oxide films deposited by APCVD process from Mo(CO) 6 in a low-temperature range - 125-200°C. We first study the correlation between CVD-process growth parameters and the structure of MoO 3 films, from one side, and the relation between their structure and optical properties, from the other side. We present a study basically on the influence on the structure of the temperature - the deposition and the post-deposition annealing ones and the influence of the vapor pressure of Mo(CO) 6 . The structure of the films is studied by different methods including infrared spectroscopy. The purpose is to see what kind of additional information can supply the IR measurements on the structure of the films in dependence of the CVD-process parameters.

Tungsten silicide (WSii) films were prepared by rapid thermal annealing (RTA) of W films obtained by chemical vapor deposition (CVD) from carbonyl precursor—W(CO)6. The RTA process proceeds at 800–1400°C in different gas environments—argon, nitrogen, vacuum, etc. Investigations of the crystal phase structure were performed by Reflection High Energy Electron Diffraction (RHEED) method. Difference in the phase composition was observed for thin and thick WSi2. Close to the surface of W films, a pure metal rich phase is formed, and at the interface W\Si, a phase rich of Si is found. Diffusion was considered to be the controlling process in the kinetics formation of WSi2. The influence of the gas environment on WSi2 was also studied. The comparison made shows that nitrogen favours WSi2 formation. Some of the samples have shown a certain degree of texturing.

Two different precursors were used to deposit W films on SiW(CO)6 and WCl6. By pyrolytic decomposition of W(CO)6 at 400 °C in argon atmosphere W thin films with well-expressed textured structure were deposited on (100)Si substrates. By hydrogen reduction of WCl6 at 750 °C in Ar, polycrystalline W films were deposited. By the carbonyl process and in the presence of ammonia and acetone, WCxNy thin films were obtained. Reflection High Energy Electron Diffraction (RHEED) method was used for structural characterization of the films. Temperature dependence of the electrical resistance of the films in the range 4.2–300 K was studied and the results are discussed in terms of films structure and composition.

Sol-gel TiO2/0.25MnO coatings on glass were obtained. They were investigated using Differential Thermal Analysis (DTA), Thermal Gravimetric Analysis (TGA) and spectrophotometry. The optimized coating was compared to a coating of pure TiO2 for passive solar control. CVD-WO3 films were obtained on different substrates by two-step technology including CVD deposition of W films, followed by a proper oxidation process.

Tungsten and molybdenum films have been deposited on silicon by the pyrolysis of hexacarbonyls at 400°C under atmospheric pressure. Auger analysis of W films produced by the pyrolysis of W(CO)6 reveals a large amount of carbon and oxygen. Post-deposition rapid thermal annealing at a temperature less than 800°C and hydrogen-containing atmosphere leads to obtaining low-resistivity thin-film materials, based on refractory metals.

The paper presents results concerning CVD thin films of transition metals (W and Mo) and their composite structures WO 2 :W and MoO 2 :Mo, as well as WO 3 films. The composite structure materials consisting of a suspension of metallic molybdenum or tungsten grains in a host matrix of metal dioxide demonstrate significant solar absorptance coupled with a high infrared reflectance, which is necessary for efficient conversion of solar energy into heat. Transition metal trioxides thin films, known as electrochromic materials have been studied with respect to the technological conditions for their growth. It is found that they start to grow up at temperatures in the range of 500 o C. Spectral transmittance and the structure of WO 3 films were investigated

By pyrolytic decomposition Of W(CO)6 in the presence of an oxygen bleed black tungsten solar selective coatings have been deposited on different substrates - quartz, silicon and stainless steel. Quartz substrates were used to check the opacity of the films deposited; the silicon substrates were used to study the possibility of obtaining low-resistance material when fully annealed and the steel substrates to study the properties of the films on substrates suitable for a large scale application. The films were obtained at a temperature of 400-degrees-C and further partially annealed in a reducing atmosphere. The dependence of the structure and chemical composition on the annealing temperature was studied, as well as reflectance measurements in the visible and in the infrared region.

By thermal decomposition of W(CO)6 and Mo(CO)6 at temperatures below 400-degrees-C and atmospheric pressure thin films on Si wafers were grown. This technology ia shown to be an alternative to the fluotide one which uses WF6 as a source material. Low resistivities together with a lack of errosion of Si substrate are possible. As-deposited films contain considerable amount of carbon and oxygen. By proper thermal annealing in H-2 atmosphere as well as by rapid thermal annealing in vacuum optimum conditions were found to obtain low resistive metal and metal silicides films. Auger electron spectroscopy and XRD-studies were used to show the connection between the chemical composition and structure of the two kinds of films on the one hand and their resistivities on the other.