Broken-Gap PtS/WSe van der Waals Heterojunction with Ultrahigh Reverse Rectification and Fast Photoresponse.

Broken-gap van der Waals (vdW) heterojunctions based on 2D materials are promising structures to fabricate high-speed switching and low-power multifunctional devices thanks to its charge transport quantum tunneling mechanism. However, the tunneling current is usually generated under both positive and negative bias voltage, resulting in small rectification and photocurrent on/off ratio. In this paper, we report a broken-gap vdW heterojunction PtS/WSe with a bilateral accumulation region design and a big band offset by utilizing thick PtS as an effective carrier-selective contact, which exhibits an ultrahigh reverser rectification ratio approaching 10 and on/off ratio over 10 at room temperature. We also find excellent photodetection properties in such a heterodiode with a large photocurrent on/off ratio over 10 due to its ultralow forward current and a comparable photodetectivity of 3.8 × 10 Jones. In addition, the response time of such a photodetector reaches 8 μs owing to the photoinduced tunneling mechanism and reduced interface trapping effect. The proposed heterojunction not only demonstrates the high-performance broken-gap heterodiode but also provides in-depth understanding of the tunneling mechanism in the development of future electronic and optoelectronic applications.