Highly Sensitive, Ultrafast, and Broadband Photo‐Detecting Field‐Effect Transistor with Transition‐Metal Dichalcogenide van der Waals Heterostructures of MoTe₂ and PdSe₂

Abstract Recently, van der Waals heterostructures (vdWHs) based on transition‐metal dichalcogenides (TMDs) have attracted significant attention owing to their superior capabilities and multiple functionalities. Herein, a novel vdWH field‐effect transistor (FET) composed of molybdenum ditelluride (MoTe 2 ) and palladium diselenide (PdSe 2 ) is studied for highly sensitive photodetection performance in the broad visible and near‐infrared (VNIR) region. A high rectification ratio of 6.3 × 10 5 is obtained, stemming from the sharp interface and low Schottky barriers of the MoTe 2 /PdSe 2 vdWHs. It is also successfully demonstrated that the vdWH FET exhibits highly sensitive photo‐detecting abilities, such as noticeably high photoresponsivity (1.24 × 10 5 A W −1 ), specific detectivity (2.42 × 10 14 Jones), and good external quantum efficiency (3.5 × 10 6 ), not only due to the intra‐TMD band‐to‐band transition but also due to the inter‐TMD charge transfer (CT) transition. Further, rapid rise (16.1 µs) and decay (31.1 µs) times are obtained under incident light with a wavelength of 2000 nm due to the CT transition, representing an outcome one order of magnitude faster than values currently in the literature. Such TMD‐based vdWH FETs would improve the photo‐gating characteristics and provide a platform for the realization of a highly sensitive photodetector in the broad VNIR region.