Studies of electrical and optical properties of SnO2:P films

The preparation and properties of phosphorus-doped SnO2 films, deposited on a heated borosilicate glass using the chemical vapour deposition, are reported in this paper. It is observed that the resistivity of the film decreases and its carrier concentration increases as the doping concentration of phosphorus increases up to 3.7 wt.%. The lowest resistivity of the film for 3.7 wt.% of phosphorus is at the optimum temperature of 400°C. The mobility increases with the phosphorus doping up to a doping concentration of 3.7 wt.% P, attaining a maximum value of 30×10−4m2V−1s−1, and thereafter it falls off with further doping concentration. The Seebeck coefficient variation with the temperature for different carrier concentrations confirms the degenerate nature of the film. The maximum transmission and the figure of merit in the wavelength region 500–800 nm are found to be 83% and 17 × 10−3 Ω−1 respectively. The optical band gap of the film is found to be 3.68 eV. The X-ray diffraction pattern for 3.7 wt.% P in solution shows peaks at (110), (101), (200) and (211). At higher doping concentration of phosphorus, the film undergoes a crystalline-to-amorphous transition.