Synthesis of large-area 2D WS2 films and fabrication of a heterostructure for self-powered ultraviolet photodetection and imaging applications

High-performance ultraviolet (UV) photodetectors have been attracting extensive attention, due to their great importance in both military and civil applications. In recent years, the rapid development of two-dimensional (2D) materials with unique and excellent optoelectrical properties has provided an ideal platform for developing high-performance photodetectors. In this work, large-area 2D WS2 films were synthesized and a WS2/GaN heterojunction was constructed. The as-fabricated WS2/GaN heterojunction device has demonstrated high-sensitivity and self-powered photoresponse properties to UV signals with a large photoresponsivity of 226 mA W-1, and an ultrahigh large specific detectivity of 4 x 10(14) Jones, as well as fast response speeds at zero bias. Furthermore, a high-resolution UV imaging result with high contrast is achieved by using the as-fabricated photodetector as a sensing pixel. The results demonstrated in this work suggest that WS2/GaN heterojunction devices have great potential in high-performance UV detection and imaging applications.