Modification on the properties of vanadium oxide films deposited from NH4F added HNO3 treated ammonium metavanadate precursor solution by spray pyrolysis technique

Pure and F doped vanadium oxide thin films were deposited on microslide glass substrates at 400 °C by spray pyrolysis technique using nitric acid treated ammonium metavanadate (NTA) aqua precursor solutions and ammonium fluoride added NTA precursor solutions respectively. X-ray diffraction study showed that the deposited films are in mixed phase of vanadium oxides (V2O5, β-V2O5, VO2 and V4O7) whereas V2O5 phase shows the preferential growth along (001) plane. Average visible transmittance of the vanadium oxide films estimated in 500-800 nm range is increased from ~73% to 82% for 20 wt% ammonium fluoride added NTA precursor solution. The wavelength at which the maximum transmittance occurred in vanadium oxide film is shifted to lower wavelength side and the band gap of vanadium oxide films is slightly modified due to addition of ammonium fluoride in the NTA solution. Surface morphology of the vanadium oxide films is influenced by the addition of various concentration of ammonium fluoride in the NTA precursor solution. The film deposited from 15 wt% of ammonium fluoride added NTA precursor solution possesses carrier concentration, mobility and conductivity of about 8.6 × 1013 cm−3, 30.1 cm2 V−1 s−1 and 4.1 × 10−4 Ω−1 cm−1 respectively which are relatively high when compared to other reports.