Published online by Cambridge University Press: 15 February 2011
Bismuth doped SnO2 films with reproducible optical and electronic properties were deposited by spray-pyrolysis on quartz and glass substrates.Deposition temperatures in the range 300°C–360°C were selected and resistivity values in the range 104−1011Ω/square were obtained. Scanning Electron Microscope (SEM) analysis and X-ray diffractometry showed that samples grown at low temperature are amorphous, while at higher deposition temperature the material structure becomes microcrystalline. The spectral transmittance of the films was measured in the UV-VIS range. The absorption coefficients were interpreted to give values of both direct and indirect band gap. The slope of Tauc's plot, which is commonly related to the degree of disorder in the material, confirmed the SEM observations. Conduction mechanisms were also studied through resistivity measurements as a function of deposition temperature. Results obtained for undoped tin oxide were also investigated for comparison.