EFFECT OF DEPOSITION AND ANNEALING TEMPERATURES ON OPTICAL BAND GAP OF SNO2 THIN FILMS DEPOSITED ON GLASS SUBSTRATE BY CHEMICAL VAPOUR DEPOSITION (CVD) METHOD

Thin films of SnO 2 were deposited by Chemical Vapor Deposition (CVD) method on glass substrates at different temperatures ranging from 6 0 ?120 0 C. Optical absorption measurements were studied by UV-VIS spectra in the wavelength ranges 300-1100 nm. The optical band gaps, absorption and extinction coefficients were determined from optical absorption data and interpreted with respect to deposition temperatures and annealing. The estimated optical band gap values were obtained between 3.72 and 4.03 eV as the substrate temperature increased. The increase in optical band gap is probably due to the change in the concentration of oxygen vacancies or defects.