Preparation and characterization of pyrolytically deposited (Co-V-O and Cr-V-O) thin films

The metal acetylacetonates of vanadium, cobalt and chromium were prepared from commercial reagents. The corresponding metal acetylacetonates were mixed in desired ratio and deposited on soda lime glass substrate by metal organic chemical vapor deposition technique. Mixed oxides thin films with atomic composition Co0.31V1.37O5 and Cr0.5V2O5 were obtained. A combination of Rutherford backscattering spectroscopy and energy-dispersive X-ray fluorescence was used for the transition element identification and atomic compositional study of the thin films. The thickness of the Co-V-O and Cr-V-O thin films was 166 and 127 nm, respectively. The optical spectra of the films were obtained using a Pye Unicam SP8-400 spectrophotometer in the ultraviolet/visible region. The result of the spectral analyses gave the optical bandgap energy of the materials. The temperature dependence of the electrical resistivity measured using the Van der Pauw method indicated that the materials are semiconducting. Their activation energy was obtained from plots of the natural logarithm of conductivity vs. the reciprocal of temperature. The sign of the thermopower shows that both materials are p-type semiconductors. (C) 2002 Elsevier Science B.V All rights reserved.