High‐Performance Infrared Photodetectors Driven by Interlayer Exciton in a Van Der Waals Epitaxy Grown HfS₂/MoS₂ Vertical Heterojunction

Abstract The van der Waals (vdW) heterojunctions of transition metal dichalcogenides (TMDCs) provide an advanced platform for interlayer exciton generation to detect the exceeding cutoff wavelengths of individual TMDCs. Herein, the first demonstration of high‐performance infrared (IR) photodetectors driven by interlayer excitons and based on HfS₂/MoS₂ vdW heterojunctions grown by chemical vapor deposition is presented. HfS₂ exhibits selective growth only on MoS₂, establishing a vertical heterojunction that effectively generates interlayer excitons. The synthesized HfS₂/MoS₂ vertical heterojunction with type‐II band alignment exhibits a low interlayer bandgap and a significantly large interface area, enabling highly efficient IR detection. Moreover, the built‐in potential in HfS₂/MoS₂ plays a pivotal role in the outstanding photoresponse by suppressing the dark current and providing gradient band bending for the interlayer exciton‐induced photocarriers to drift toward each electrode. The HfS₂/MoS₂ photodetector exhibits remarkable performance, achieving a detectivity (D*) of ≈7 × 10¹³ Jones at 1550 nm, D* of ≈2 × 10¹⁴ Jones at 980 nm, and fast response time of 60 µs, surpassing previously reported 2D photodetectors. Overall, the successful demonstration of a photodetector based on vdW epitaxial HfS₂/MoS₂ paves the way for the advancement of large‐scale high‐performance IR sensors.