Junction Field-Effect Transistors Based on MoSe2/WSe2 Heterostructures for High-Performance Photodetection

Two-dimensional (2D) materials show great potential in creating high-performance ultracompact photodetectors. Existing 2D photodetectors are usually designed based on a photogating effect or photovoltaic effect. However, achieving a balance between photodetectivity and photoresponsivity presents a significant challenge due to increased dark currents at trap level recombination or the lack of a gain mechanism. Herein, we rationally design a gate-tunable junction field-effect transistor photodetector based on MoSe₂ and WSe₂. With proper modulating the depletion layer and Schottky barrier using source-drain and gate bias, the device can effectively reduce dark current, resulting in an ultrahigh photodetectivity of 1.55 × 10¹³ Jones and an ultrahigh optical switching ratio of 10⁴. Furthermore, our photodetector exhibits a high photoresponsivity of 476 A/W and an ultrafast response time of 50 μs under 635 nm laser irradiation with an extended detection capability to the 1550 nm band. These outstanding performances highlight the potential of 2D heterojunctions in addressing the growing demands of next-generation photonic sensors.