ReS₂/Black Arsenic–Phosphorus van der Waals Heterojunction for a High-Performance Photodetector

The van der Waals heterojunction has drawn great attention for high-performance photodetectors due to its outstanding physical properties. However, the practical application of the photodetector is restricted by extremely large dark current and low responsivity. Herein, we report a highly sensitive photodetector constructed with ReSn2 and AsP with a p–n diode behavior. The dark current is reduced successfully by more than an order of magnitude due to a built-in electric field and strong interlayer coupling at the heterojunction interface. The heterostructure photodetector displays a high responsivity of 12.56 A W−1 under illumination with 532 nm laser light. An external quantum efficiency (EQE) of 2935% and a specific detectivity (D*) rate of 5 × 1010 Jones are achieved. In addition, a millisecond-level response speed is tested, which is 2 orders of magnitude lower than those of the ReS2 device. The separation of the photogenerated electrons and holes at the interface plays the crucial important role in the improvement of the performance for the heterojunction photodetector. 2D van der Waals heterostructures present a feasible way for improving responsivity, which is of great significance in the application of photodetectors.