A dual-band photodetector based on a mixed-dimensional WSe2/GaN junction

Abstract

This work demonstrates a WSe₂/GaN heterojunction with different bandgaps and dimensionality for a high performance visible/ultraviolet dual-band photodetector. Two-dimensional (2D) p-type WSe₂ was stacked on top of three-dimensional (3D) n-type GaN, enabling good construction of p–n junction at the interface, and thus exhibiting an excellent current rectification behavior and junction field-effect property. As a junction field-effect transistor (JFET), the device with WSe₂ as a channel and GaN as a gate exhibits good transfer and output characteristics. In such a configuration, the device can be operated in the visible band with a responsivity of 98.67 A W⁻¹ under 635 nm light illumination. By configuring the source/drain terminals on GaN, the device where GaN acts as a channel and WSe₂ is sensitized on top is switched into the ultraviolet band. Under 325 nm light illumination, the responsivity (R) and specific detectivity (D*) can reach up to 7863.5 A W⁻¹ and 1.27 × 10¹⁴ Jones, respectively, far exceeding the state-of-the-art 2D- and GaN-based ultraviolet photodetectors. This work develops a mixed-dimensional WSe₂/GaN junction for high performance dual-band photodetectors.