Dynamic Band-Alignment Modulation in MoTe2/SnSe2 Heterostructure for High Performance Photodetector

For two-dimensional (2D) layered material heterojunctions, dynamic modulation of band alignments allows for the design of devices with flexible multi-functional applications. In this paper, a device structure is presented based on a MoTe2/SnSe2 field-effect transistor. By applying a bias voltage to the electrostatic gate, the gate voltage is adjusted from negative to positive, causing the heterojunction to transition from type-III band alignment to type-II band alignment. The working mechanism and device performance of the heterojunctions with different band alignments are investigated. The device exhibited outstanding detection range (from ultraviolet to infrared), detectivity (2.42 x 10(9) Jones), and speed (1.3 ms). Under a positive gate voltage, a higher ratio of light current to dark current (2x10(3)) is achieved. To further demonstrate the potential of the high-performance devices, their reliability is confirmed through their performance in image recognition using deep learning.