Lateral and Vertical MoSe-MoS Heterostructures via Epitaxial Growth: Triggered by High-Temperature Annealing and Precursor Concentration.

Atomically thin transition-metal dichalcogenide (TMDC) heterostructures have attracted increasing attention because of their unprecedented potential in the fields of electronics and optoelectronics. However, selective growth of either lateral or vertical TMDC heterostructures remains challenging. Here, we report that lateral and vertical MoS/MoSe epitaxial heterostructures can be successfully fabricated via a one-step growth strategy, which includes triggering by the concentration of sulfur precursor vapor and a high-temperature annealing process. Vertically stacked MoS/MoSe heterostructures can be synthesized via control of the nucleation and growth kinetics, which is induced by high sulfur vapor concentration. The high-temperature annealing process results in the formation of fractured MoSe and in situ epitaxial growth of lateral MoSe-MoS heterostructures. This study has revealed the importance of sulfur vapor concentration and high-temperature annealing processes in the controllable growth of MoSe-MoS heterostructures, paving a new route for fabricating two-dimensional TMDC heterostructures.