Dual Orthogonal‐Stacked Ti₃C₂T_x/WS₂/Si Bulk Heterostructure for Ultrafast and Sensitive Self‐Powered Broadband Photodetector with Weak Light Detection Capability

Abstract Optoelectronic devices based on 2D materials/3D van der Waals heterostructures (vdWhs) have garnered considerable interest owing to their seamless integration and remarkable photodetection capabilities. However, the present device structure‐dependent photogenerated carrier transport and extraction still suffers from more serious challenges. Here, vertically oriented WS 2 nanosheet arrays are prepared controllably via magnetron sputtering technique on an n‐type silicon substrate, accompanied by a follow‐up transversely distributed 2D MXene layer, to construct a dual orthogonal‐stacked (DOS) heterostructure. This DOS strategy effectively utilizes the efficient charge transport channel properties inside a 2D‐material plane to fundamentally suppress carrier recombination and promote efficient carrier transport and extraction. The photodetectors (PDs) demonstrate excellent broadband photoresponsefrom ultraviolet to short‐wavelength infrared (254–1650 nm), achieving a photoresponsivity of 793 mA W −1 , a high light‐to‐dark current ratio of over 10 3 at 500 nW cm −2 , high response speeds (500 ns/31.1 µs) and a specific detectivity of 1.03 × 10 14 Jones at zero bias. Additionally, the PDs maintain good long‐term stability and repeatability under high pulsed light (500 kHz). This research provides a guidepost and theoretical support for the design of high‐performance 2D/3D heterojunction PDs and promotes the development and advancement of inorganic 2D‐based PDs.