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

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 SnSe2/Bi2Se3/MoTe2 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 x 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 SnSe2/Bi2Se3 interface and the reversed band edge from depletion to accumulation mode at Bi2Se3/MoTe2 interface. In addition, a faster response speed of 553/583 mu s 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 MoTe2/SnSe2 heterojunction. These results demonstrates the potential as a candidate for back-to-back type-III band alignment in low power optoelectronics.