Polymorphic In-Plane Heterostructures of Monolayer WS2 for Light-Triggered Field-Effect Transistors.

The realization of next-generation transition-metal dichalcogenide based nanoscale devices demands stringent control over coherent in-plane heterostructures of atomically thin monolayers with exceptional properties. In this paper, we report atmospheric-pressure chemical vapor deposition growth of large-domain, coherent polymorphic in-plane heterostructures of monolayer WS₂ on a SiO₂/Si substrate with intriguing optical and electronic properties. The formation of in-plane heterostructures with 1H and 1T polymorphs was extensively analyzed using a variety of spectroscopic as well as microscopic techniques, along with lifetime luminescence imaging. High-angle annular dark-field scanning transmission electron microscopy revealed coexistence of the heterophases in monolayer WS₂ heterostructures. Back-gated photoconductivity measurements in nanoscale field-effect-transistor device geometry and the rational design of a WS₂ heterostructure pattern demonstrate optoelectronic applications. [ABSTRACT FROM AUTHOR]