High-Performance Broadband Photodetector Based on Tunneling Heterostructure MoS₂/PdSe₂

The two-dimensional (2D) material PdSe₂ is an ideal material for preparing a high-performance broadband photodetector because of its narrow and tunable band gap. However, poor light absorption limits the application of single PdSe₂. Here, a PdSe₂-based van der Waals (vdWs) heterostructure MoS₂/PdSe₂ is selected to realize broadband photodetection after a screening of theoretical calculations. Different from most other PdSe₂-based heterostructures, MoS₂/PdSe₂ here is a heterostructure with a type-I band alignment, where the conduction band minimum (CBM) and valence band maximum (VBM) both come from PdSe₂. It exhibits high-performance broadband photodetection, for example, in the case of a 600 nm illumination, the heterostructure shows a responsivity of 51.4 A/W and a detectivity of 2.28 × 10¹⁰ cm Hz^1/2 W^-1; in the case of a near-infrared illumination of 900 nm, it has a responsivity of 6.11 A/W and a detectivity of 2.71 × 10⁹ cm Hz^1/2 W^-1. Our analysis indicates that the good performance originates from a direct tunneling (DT) mechanism in the heterostructure, which not only reduces the recombination of carriers but also improves the carrier collection rate.