Broadband and Polarized Photodetector Based on Sb₂Te₃/WS₂ van der Waals Heterojunction Nanostructures

Van der Waals (vdW) heterostructures based on two-dimensional (2D) transition-metal dichalcogenides (TMDs) without a crystal lattice matching constraint show great potential for high-performance optoelectronic devices. In this study, a Sb2Te3/WS2 vdW heterostructure based on TMDs and topological insulators is fabricated for broadband photodetection spanning the visible to short-wave infrared wavelength bands, which demonstrates high responsivity, ambipolar photoresponse (negative and positive), self-powered, and polarization-sensitive detection capabilities. Due to special Z-scheme charge transfer and the efficient light-harvesting ability in the heterostructure, the device exhibits a broadband response ranging from 400 to 2200 nm, achieving a high responsivity of 0.429 A/W and a detectivity of 1.89 × 109 Jones at 1 V bias under 1310 nm laser illumination. Furthermore, the devices demonstrate a high degree of linear polarization sensitivity, with a dichroic ratio of ∼2.2 at 650 nm and up to ∼4 at 1310 nm, primarily attributable to the anisotropy of light absorption and the stacking direction of the crystal. Overall, this study reveals the great potential of Sb2Te3/WS2 vdW heterostructures for high-performance polarization-sensitive broadband photodetectors.