Abstarct: Transparent conducting oxide (TCO) materials have received a great deal of interest due to their favorable physical properties such as low resistivity, high transmittance in the visible and near infrared regions and good adherence to substrates, for variety of technological applications. Tin oxide (SnO2) is a direct wide band gap (3-4 eV), n-type semiconductor and a deposition of this material on p-type Si may lead to a diode structure. In the present thesis first we have investigated the effects of substrate temperature and impurity doping concentration of antimony (Sb) on crystal structure, electrical and optical properties of thin (~ 200 nm) SnO2 films grown by spray pyrolysis method. Then a pure tin oxide laxyer with optimum conditions has been deposited on top of flat and porous silicon surfaces and studied its electrical properties. In the first step we found a substrate temperature of 425 °C leads to a maximum figure of merit. For this laxyer the material has a maximum band gap of 3.75 eV and a minimum resistivity of 5.1×10-3 Ωcm. In this laxyer the average optical transmittance in the wavelength range of 500-800 nm is about 85 percent. Through impurity doping process with antinomy up to 1.5 weight percent we found that the laxyer with 0.5% impurity concentration has a maximum figure of merit while its band gap is 3.73 eV and its electrical resistivity is 2.22×10-3 Ωcm. Using the optimum growth condition for pure SnO2 it was deposited on flat and porous (with different anodization times) Si wafers. We found all these devices have a rectifying I-V characteristic. In addition our calculations showed that while sample with a flat Si surface has an ideality factor (n) of 5 and series resistance (rs) of 19 Ω, these parameters rises in samples with porous surfaces with a factor of 2 and 20, respectively. These variations are assigned to the presence of the localized states as well as the insulator laxyer at the interface between the tin oxide laxyer and silicon substrate.