High performance self-powered CuZnS/GaN UV photodetectors with ultrahigh on/off ratio (3 × 108)

Abstract

The heterojunction UV photodetector based on p-CuZnS and n-GaN is prepared by a simple chemical bath deposition. The CuZnS/GaN film device shows a significantly enhanced photocurrent at 3 V and 350 nm, a good rectifying behavior (ratio of 19 000 at ±3 V) and a large open circuit voltage (0.55 V). Furthermore, the CuZnS/GaN photodetector exhibits excellent self-powered characteristics under 350 nm light illumination, including a high photocurrent (19 μA), a fast response speed (0.14/40 ms) and an ultrahigh on/off ratio (3 × 10⁸). More importantly, the CuZnS/GaN photodetector presents a large detectivity of 8 × 10¹³ Jones and an ultrahigh linear dynamic range of 137 dB at 320 nm light illumination at zero bias. These results suggest that the CuZnS/GaN film devices have great potential as high-performance self-powered UV photodetectors for practical applications.