Regulation of structural, electrical and optical properties of Sb-doped SnO2 films prepared with different O2 flow rates by rapid thermal annealing

Abstract

Effects of rapid thermal annealing (RTA) on the structure and photoelectric properties of Sb-doped SnO2 (ATO) films have not been systematically reported. In this study, ATO films were prepared by RF magnetron sputtering under different O2 flow rates (0, 15, 30 and 45 sccm), and then were subjected to RTA at different temperatures (400, 600 and 800 °C) in atmospheric environment. The results show that preferred orientations of ATO films changes from (101) to (110) crystal-plane and crystallite size increases with increasing O2 flow rate. RTA cannot change the films’ preferred orientation and crystallite size except for the film deposited in Ar atmosphere (0 sccm O2), but it can decrease the compressive stress in the films. The as-deposited and annealed films with low transmittance in visible light range (TVis) have obvious Raman scattering peak, and scattering peak of Eg vibration mode is stronger in the appearing Raman scattering peaks. Increasing O2 flow rate degrades electrically conductive properties of the films, increases TVis and makes optical band-gap (Eopt) first increase and then decrease. With increasing RTA temperature, the electrically conductive properties enhance and Eopt increases for the films deposited with all O2 flow rates, but TVis basically decreases for the films deposited with O2 flow rate of 15–45 sccm. Currently, the ATO film deposited at 15 sccm O2 and annealed at 600 °C has the best transparent conductive properties (the resistivity, sheet resistance, TVis and figure of merit are 2.09 × 10−3 Ω cm, 67 Ω/sq., 77.12%, and 1.11 × 10−3 Ω−1, respectively). In addition, element chemical states and point defects in the films were analyzed by XPS. Meanwhile, influence mechanisms of O2 flow rate and RTA on structure and properties of the films were discussed.