Effect of Annealing on the Morphology, Structure and Photoelectric Properties of AZO/Pt/FTO Trilayer Films

Abstract

Aluminum-doped zinc oxide/platinum/fluorine-doped tin oxide (AZO/Pt/FTO) trilayer films were prepared by sputtering 5-nm-thick Pt layers and 150-nm-thick AZO layers in sequence on commercial FTO glass. The effects of one-step annealing and layer-by-layer annealing on the morphology, structure and photoelectric properties of the AZO/Pt/FTO trilayer films were comparatively analyzed. It is found that the both annealing approaches increased the grain size and improved the crystallinity of the films, leading to enhancement in transmittance and conductivity. However, layer-by-layer annealing led to the formation of quasi-continuous or continuous AZO layers, different from the sparsely distributed AZO particles brought about by one-step annealing, resulting in excellent optical and electrical properties. Specifically, after layer-by-layer annealing at 400 °C for both Pt and AZO layers, the AZO/Pt/FTO trilayer film showed an increase in average transmittance from 71.3% to 85.3% and a decrease in sheet resistance from 7.5 to 5.6 Ω/□, leading to the highest figure of merit of 3.64 × 10−2 Ω−1.