2D Double Heterostructure Infrared Photodetector with Type‐III Band Alignment by Incorporating Bi2Se3 Layer

Abstract Two‐dimensional (2D) self‐powered photodetectors have attracted considerable attention due to their exceptional sensitivity, and low dark current. However, the poor responsivity of single heterojunctions with type‐III band alignment is primarily attributed to band‐to‐band tunneling. The implementation of a double heterojunction has the potential to enhance photovoltaic responsivity, enable broadband detection, and improve response speed. In this study, a back‐to‐back type‐III band alignment based on SnSe 2 /Bi 2 Se 3 /MoTe 2 double heterostructure by dry transfer method is designed. As a result, it exhibited an impressive photovoltaic performance in the overlapping region. Achieving a maximum responsivity (R), external quantum efficiency (EQE), photoelectric conversion efficiency (PCE), and specific detectiviy (D * ) of 493 mA W −1 , 76 %, 3 % and 1.8 × 10 11 Jones at a gate voltage (V g ) of 60 V under 808 nm illumination. It can be ascribed to the effective depletion region at the SnSe 2 /Bi 2 Se 3 interface and the reversed band edge from depletion to accumulation mode at Bi 2 Se 3 /MoTe 2 interface. In addition, a faster response speed of 553/583 µs and a lower dark current of 2.9 pA can be obtained. Moreover, this double heterostructure achieves better photovoltaic performance with V g compared to the single MoTe 2 /SnSe 2 heterojunction. These results demonstrates the potential as a candidate for back‐to‐back type‐III band alignment in low power optoelectronics.