Dual Orthogonal-Stacked Ti3C2Tx/WS2/Si Bulk Heterostructure for Ultrafast and Sensitive Self-Powered Broadband Photodetector with Weak Light Detection Capability

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 WS₂ 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 10³ at 500 nW cm⁻², high response speeds (500 ns/31.1 µs) and a specific detectivity of 1.03 × 10¹⁴ 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.