A two-dimensional Te/ReS2 van der Waals heterostructure photodetector with high photoresponsivity and fast photoresponse

Two-dimensional (2D) semiconductors are the building blocks for high-performance optoelectronic devices. However, the performance of photoconductive photodetectors based on 2D semiconductors is hampered by low photoresponsivity and large dark current. Herein, a van der Waals heterostructure (vdWH) composed of rhenium disulfide (ReS2) and tellurium (Te) is fabricated. The Te/ReS2 vdWH photodetector exhibits a sensitive and broadband photoresponse and has high photoresponse on/off ratios under ultraviolet and visible light illumination, especially over 10(2) in visible light. The Te/ReS2 vdWH photodetector achieves the responsivity of 7.9 A W-1 at 365 nm, 3.02 A W-1 at 450 nm, 2.37 A W-1 at 532 nm, and 2.45 A W-1 at 660 nm. In addition, the device achieves a high specific detectivity of 10(11) Jones and a fast photoresponse speed of 11.9 mu s. Such high responsivity could be attributed to the efficient absorption of phonons by the Te/ReS2 vdWH and the high-quality heterostructure interfaces with a small amount of trap states. The highly crystalline structure of Te/ReS2 with a low density of defects reduces the grain boundary scattering, leading to the rapid diffusion of charge carriers. Moreover, the Te/ReS2 vdWH device exhibits a photovoltaic effect and can be employed as a self-powered photodetector (SPPD), which is sensitive to visible light of 450 nm, 532 nm, and 660 nm. Our findings demonstrate that the Te/ReS2 vdWH photodetector is an ideal building block for the next-generation electronic and optoelectronic devices in practical applications.