A Single-Step-Grown Semiconducting vdW Heterostructure of Tungsten Oxide – Sulfide for High-Performance Photodetection

Ultrathin semiconducting van der Waals (vdW) heterostructures based on transition metal dichalcogenides (TMDs) play a critical role in developing next-generation electronic and optoelectronic devices. The replacement of one component of the heterostructure by transition metal oxides (TMOs) certainly brings in numerous benefits including long-term stability and novel functionalities. However, the single-step chemical-vapor deposition growth of TMOs/TMDs vdW heterostructures, as a highly desired approach for large-scale fabrication and practical implementation, is challenging due to contradictory growth atmospheres of TMOs and TMDs. Here, the single-step growth of an ultrathin WO3–x/WS2 vdW heterostructure based on the quantity-driven discrepant interaction between S and the precursor, in which S induces sulfidation to produce WS2 in the S-rich phase and is changed to the reduction role to obtain sub-stoichiometric WO3–x in the S-deficient phase is realized. Both WO3–x and WS2 exhibit semiconducting properties with a favorable type-II band alignment. A wide response across the entire visible spectrum with a large photo-responsivity of 4375 A W−1, a detectivity of 5.47 × 1011 Jones, and sub-ms switching kinetics at 405 nm is achieved without gating bias, which is significantly improved over other reported ultrathin vdW heterostructures. This study demonstrates the possibility of single-step-growing TMOs/TMDs vdW heterostructures and their strong potential in high-performance optoelectronic devices.