DC-sputtered ZnO nanoflake thin films for high-performance self-powered UV photodetectors

Abstract

Here, we report a self-powered metal–semiconductor–metal ultraviolet (UV) photodetector based on a compact ZnO thin film deposited by direct current magnetron sputtering onto a p-type silicon substrate. Unlike widely studied nanowires or nanoparticle films, the sputtered ZnO thin film forms a continuous and densely packed network of nanoflakes that enhances light absorption and charge transport. The resulting device exhibits rectifying characteristics of Schottky contacts and achieves excellent zero-bias performance, including a high responsivity of 0.68 A/W, a detectivity of 2.1 × 1012 Jones, an external quantum efficiency of 2.32 × 102%, and a fast transient photocurrent with rise and decay times of 68 ms and 138 ms, respectively, under 365 nm irradiation at 2.8 mW/cm2. These results highlight the potential of sputtered ZnO nanoflake thin films as an industrially compatible platform for cost-effective, high-speed, self-powered UV photodetectors.