Epitaxial Growth of SnS2/WS2–WSe2 Bilayer P–N Hybridized Heterojunctions for Multifunctional Optoelectronic Devices

Two-dimensional P–N hybridized heterojunctions (HHJs) with both lateral and vertical interfacial structures are expected to integrate the characteristics of both lateral and vertical heterojunctions, demonstrating substantial potential for next-generation optoelectronic applications. In this study, using a vapor growth method, we synthesized SnS2/WS2–WSe2 bilayer P–N HHJs. We also integrated type-II (SnS2/WS2) and type-III (SnS2/WSe2) band alignments on a single-crystal bilayer nanosheet. We achieved well-aligned lattice orientation between SnS2 and WS2 (WSe2), and the measured periodic Moiré superlattice was about 2.10 nm (3.20 nm). We detected significant photoluminescence quenching in the vertical heterojunction regions, indicating efficient charge transfer across the vertical interfaces. The fabricated field-effect transistors based on the heterobilayer demonstrated significantly enhanced electrical performance, with substantially improved on-state current and carrier mobility compared to their WS2 (WSe2) monolayers. The SnS2/WS2–WSe2 HHJ-based device exhibited obvious current rectification in dark conditions and demonstrated a remarkable photovoltaic response under a 520 nm laser illumination. Finally, the self-powered photodetector showed good optical switching stability and fast response time (rise time: 790, fall time: 810 μs). The synthesis of SnS2/WS2–WSe2 bilayer P–N HHJs provides a way to create advanced multifunctional optoelectronic systems with high performance.