Optical and structural characteristics of tin oxide thin films deposited by filtered vacuum arc and spray pyrolysis

Tin oxide (SnO2) thin films were deposited on commercial microscope glass and UV fused silica substrates (UVFS) using spray pyrolysis and filtered vacuum arc deposition (FVAD) system. During deposition, the substrates temperature was kept at 400 degrees C. The structure and composition were determined using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The XRD patterns of SnO2 thin films deposited with the two systems on hot substrates were found to be polycrystalline. The average transmission of the films in the VIS was 80% to 85%. The film optical constants were determined by normal incidence transmission measurements. The refractive indices of EVA deposited films were in the range 2.11 to 2.0, and those of spray deposited ones were 1.97 to 1.93. The extinction coefficients of the deposited films were in the range 0.29 and 0.11 to approximately 0 for FVAD and spray pyrolysis, respectively, depending on wavelengths. The optical band gap, E-g, was determined from the dependence of the absorption coefficient on the photon energy at short wavelengths, and were 3.80 eV and 3.90 eV for spray pyrolysis and EVA deposited SnO2 thin films, respectively. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim