Near‐Direct Band Alignment of MoTe2/ReSe2 Type‐II p‐n Heterojunction for Efficient VNIR Photodetection

Abstract

AbstractVisible near infrared (VNIR) transition‐metal dichalcogenides (TMDs) photodetectors have attracted attention due to their unique electronic and optoelectronic properties. Herein, the photodetection performance of a novel MoTe2/ReSe2 van der Waals heterojunction (vdW HJ) diode is studied in the VNIR region. Density functional theory calculations reveal the formation of type‐II band alignment, which is beneficial for the design of a MoTe2/ReSe2 HJ diode with better optoelectronic properties. A superb rectification ratio of ≈1 × 104 is obtained via gate engineering, in which the ambipolar nature of MoTe2 enables a transition from p+–i to n–n+ state. In addition, the diode exhibits an excellent figure of merit for photodetection. The excellent diode performance is demonstrated by a high responsivity of 5.6 × 102 A W−1, an excellent detectivity of 8.1 × 1013 jones, and an external quantum efficiency of 9.5 × 102. Moreover, fast rise and decay times of 2 and 4 ms, respectively, are observed under illumination. The significant improvement is attributed to the combination of an intra‐TMD band‐to‐band transition and an inter‐TMD charge transfer process in the MoTe2/ReSe2 vdW HJ. This study provides an opportunity for advancing the prospects of TMDs in next generation optoelectronics.