Highly transparent conductive F-doped SnO2 films prepared on polymer substrate by radio frequency reactive magnetron sputtering

Abstract

F-doped SnO2 (FTO) films have excellent optical-electrical properties and have been widely used, but the preparation of FTO film on the surface of flexible polymer substrate by magnetron sputtering has not been reported. In this study, Sn-SnF2 mixture was used as the target, and then the FTO film was prepared by reactive magnetron sputtering on the surface of the polyethylene terephthalate substrate at substrate temperature of room temperature, 60 and 100 °C. The results show that highly transparent conductive FTO films can be obtained by optimizing the O2 flow rate at each substrate temperature. In general, as the substrate temperature increases, the optimized range of O2 flow rate shifts to the direction of lower O2 flow rate and the corresponding transparent conductive properties are slightly enhanced. Currently, the films show sheet resistance of 209–423 Ω/sq., transmittance in visible-light range of 84.4–90.3% and figure of merit of 5.09–12.9 × 10–4 Ω–1, which is comparable with those of previously reported SnO2-based films. At the same time, the films have better bending performance at the bending radius of 20 mm, but they have poor damp-heat stability. In addition, the influence of substrate temperature and O2 flow rate on structure (thickness, crystallinity and surface roughness) and energy gap of the films is also investigated.