ReS2/Si 2D/3D vertical heterojunction as a self-powered photodiode

2D/3D van der Waals heterostructures provide an excellent platform for high-performance optoelectronic systems by combining the intrinsic properties of 2D and 3D materials. In this study, we fabricate and study a type II ReS2/Si van der Waals 2D/3D vertical heterojunction with multi-mode photodetection. In the dark, the heterojunction exhibits diode-like behavior with a low reverse current and a high rectification ratio of ∼103. Under illumination, the device shows a linear response to the light intensity. The ReS2/Si photodetector exhibits stable and repeatable switching behavior and can be operated in self-powered mode with a responsivity of about 0.10 mA/W at 10 mW incident power and a time response of 300 μs. Based on first-principles calculations, we propose a model to elucidate the photoconduction mechanisms occurring in the ReS2/Si heterostructure.