An ultrafast MoTe2-based photodetector via MoO3 interface layer optimization

Abstract

Two-dimensional (2D) molybdenum ditelluride (MoTe₂) has attracted wide attention due to its unique crystal structure and outstanding optical and electrical properties in photodetection. However, as a bipolar material, MoTe₂ is more sensitive to environmental factors compared to other 2D materials. Interface issues in MoTe₂ devices severely affect their photodetection performance. Here, we focus on improving the material and dielectric interface and propose a highly sensitive photodetector based on a MoO₃-MoTe₂ heterostructure. Through interface engineering, MoO₃ not only serves as a substrate dielectric layer to improve the material and dielectric interface but also forms a heterostructure with MoTe₂, inducing charge transfer and realizing a p-n junction with a large built-in electric field. Due to these characteristics, the device exhibits excellent photodetection performance with an open-circuit voltage V_oc = 0.46 V and short-circuit current I_sc = 210nA. In 532 nm self-powered mode, the responsivity of the device is 2 mA /W, with a light-to-dark ratio of approximately 10⁵, rise/decay times of 78/49 μs, and a cutoff frequency exceeding 7 kHz. This work provides inspiration for the future development of high-performance photodetectors, with MoO₃ as a substrate showing promise for achieving high optical responsivity and fast response in 2D material photodetectors.