The influence of deposition temperature and annealing temperature on Ga-doped SnO2 films prepared by direct current magnetron sputtering

Abstract

Transparent Ga-doped tin oxide (GTO) thin films were fabricated on quartz glass from a (SnO2 + Ga2O3) mixture ceramic target by direct current (DC) magnetron sputtering in Ar ambient gas at a working pressure of 4.10−3 torr. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Hall-effect and UV–vis spectral measurements were performed to characterize the deposited films. The films could be given p-type electrical properties by supplying energy, such as kinetic (by controlling pressure) or thermal (by controlling temperature substrate) energy. However, kinetic energy caused film stress; therefore, we investigated the substrate temperature of the films in two ways. In the first method, films were deposited directly with different temperatures; in the second method, post-deposition annealing in Ar ambient gas after deposition at 400 °C was used. The deposited films showed p-type conduction, polycrystalline tetragonal rutile structure, and the average transmittance was above 80% in the visible light range after annealing at the optimum temperature of 550 °C for 2 h. The results for the best conductive film showed a low resistivity of 0.63 Ωcm and a sheet resistance of 15.7 kΩ/sq, a hole concentration of 3.3 × 1018 cm−3, and a Hall mobility of 3.01 cm2 V−1 s−1 with thickness is about 400 nm. In addition, p-type conductivity was also confirmed by the non-linear characteristics of a p-type GTO/n Si heterojunction.