K.A. Gesheva

Investigation of CVD molybdenum oxide films

Abstract Thin films of molybdenum oxide were obtained by atmospheric pressure Chemical Vapor Deposition (CVD) method at two deposition temperatures of 150 and 200 °C. The precursor used was Mo(CO) 6 in Air+O 2 atmosphere. The films were deposited on different substrates (Si wafer, glass and conductive SnO 2 :Sb covered glass) and showed good adhesion. They were characterized by XRD measurements, IR spectroscopy, Transmission Electron Microscopy (TEM) and UV–VIS spectroscopy. The coatings were uniform and had a good optical behavior with 70–80% transmittance in the visible region.

Structural and Optical Properties of CVD Thin Tungsten Oxide Films

Thin amorphous and polycrystalline tungsten oxide films were prepared by chemical vapour deposition at atmospheric pressure from a metalorganic precursor - tungsten hexacarbonyl. The dependence of the structural and optical properties of tungsten oxide films on the technological conditions has been investigated by XRD, Raman spectroscopy and spectroscopic ellipsometry.

Spectroscopic characterization of CVD-molybdenum oxide films

Abstract By chemical vapor deposition at atmospheric pressure using Mo(CO) 6 precursor and Ar/O 2 gas mixture, thin MoO 3 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 MoO 3 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, E og , 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.

Electrochromic behavior in CVD grown tungsten oxide films

Solid state electrochemical devices (ECDs) for smart windows, large area displays and automobile rearview mirrors are of considerable technological and commercial interest. In this paper, we studied the electrochromic properties of amorphous and polycrystalline CVD carbonyl tungsten oxide films and the possibility for sol-gel thin TiO 2 film to play the role of passive electrode in an electrochromic window with solid polymer electrolyte.

Structural transformations and their relation to the optoelectronic properties of chromium oxide thin films

The crystallization behavior of chemically vapor deposited chromium oxide films was characterized by X-Ray diffractometry and the vibrational properties of the films were analyzed by Fourier transform infrared (FTIR) spectroscopy as a function of the annealing temperature and the technological conditions. The effect of the oxygen content in the CVD reactor on the optical characteristics (complex refractive index, optical band gap) was considered.

Sol-gel and CVD-metal oxide coatings for solar energy utilization

Sol-gel TiO20.25MnO 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.

Chemically vapor-deposited black molybdenum films of high IR reflectance and significant solar absorptance

Abstract Black molybdenum thin films fabricated by chemical vapor deposition demonstrate a significant solar absorptance coupled with a high IR reflectance. Because antireflected black molybdenum demonstrates such spectral selectivity in a coating of simple design, it is an attractive candidate for use in photothermal solar energy conversion. Films deposited onto Incoloy alloy 800 and stainless steel 316 have survived testing in vacuum at 500 °C and in air at 350 °C. If the process parameters are varied during deposition, this can lead to black molybdenum with a graded composition.

Deposition and study of CVD—tungsten and molybdenum thin films and their impact on microelectronics technology

Abstract 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.

Black molybdenum photothermal converter layers deposited by pyrolytic hydrogen reduction of MoO2Cl2

Abstract Black molybdenum thin films, combining high infrared reflectance with significant solar absorptance, have been produced by pyrolytic hydrogen reduction of MoO 2 Cl 2 in the temperature range 550–710°C on quartz as well as metal substrates. A respectable selectivity and significant temperature durability at 500°C in vacuum are obtained.

Characterization of CVD Chromium Oxide Thin Films

Thin films of chromium oxide were obtained by the atmospheric pressure CVD method at a deposition temperature of 200 °C. The used precursor was Cr(CO) 6 in Ar + O 2 atmosphere. The films were deposited on different substrates (Si substrate, glass and conductive SnO 2 :Sb covered glass) and showed good adhesion. They were characterized by XRD measurements, IR spectroscopy, transmission electron microscopy and VIS spectroscopy. The coatings are uniform and have a good optical behavior with 60-70% transmittance in the visible region.