Controllable Epitaxial Growth of Large-Area MoS2/WS2 Vertical Heterostructures by Confined-Space Chemical Vapor Deposition

The controllable large-area growth of single-crystal vertical heterostructures based on 2D transition metal dichalcogenides (TMDs) remains a challenge. Here, large-area vertical MoS2/WS2 heterostructures are synthesized using single-step confined-space chemical vapor epitaxy. The heterostructures can evolve into two different kinds by switching the H-2 flow on and off: MoS2/WS2 heterostructures with multiple WS2 domains can be achieved without introducing the H-2 flow due to the numerous nucleation centers on the bottom MoS2 monolayer during the transition stage between the MoS2 and WS2 monolayer growth. In contrast, isolated MoS2/WS2 heterostructures with single WS2 domain can be obtained with introducing the H-2 flow due to the reduced nucleation centers on the bottom MoS2 monolayer arising from the hydrogen etching effect. Both the two kinds of the vertical MoS2/WS2 heterostructures feature high quality. The photodetectors based on the isolated MoS2/WS2 heterostructures exhibit a high responsivity of 68 mA W-1 and a short response time of 35 ms. This single-step chemical vapor epitaxy can be used to synthesize vertical MoS2/WS2 heterostructures with high production efficiency. The new epitaxial growth approach may open new pathways to fabricate large-area heterostructures made of different 2D TMDs monolayers of interest to electronics, optoelectronics, and other applications.

Automated summary

In this study, large-area vertical MoS2/WS2 heterostructures were synthesized using single-step confined-space chemical vapor epitaxy. By switching the H-2 flow on and off, two different kinds of heterostructures can be obtained, both with high quality. Photodetectors based on isolated MoS2/WS2 heterostructures exhibit excellent performance.