Type-II WS2/AsP van der Waals heterojunctions with high rectification ratio and high detectivity

Abstract

Photodetectors based on two-dimensional materials have attracted significant attention due to their unique structure and outstanding optoelectronic properties. However, large dark current and extended response time have become bottlenecks for further practical application. In this work, a WS₂/AsP van der Waals heterojunction (vdWHs) with a type-II band structure has been fabricated. The built-in electric field at the interface can effectively suppress dark currents and separate photo-generated charge carriers, enhancing photoelectric characteristics. At room temperature, the device exhibits a switching ratio of 10⁷ and a rectification ratio of 10⁵. Under a 532 nm laser illumination, the photodetector presents outstanding characteristics: the detectivity exceeds 1.72 × 10¹³ jones, the responsivity achieves approximately 14.6 A W⁻¹, the external quantum efficiency reaches up to 4120%, and the response time is in the millisecond range. Our results indicate that WS₂/AsP heterojunctions hold promising prospects for future optoelectronic applications.