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

Abstract The controllable large‐area growth of single‐crystal vertical heterostructures based on 2D transition metal dichalcogenides (TMDs) remains a challenge. Here, large‐area vertical MoS 2 /WS 2 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: MoS 2 /WS 2 heterostructures with multiple WS 2 domains can be achieved without introducing the H 2 flow due to the numerous nucleation centers on the bottom MoS 2 monolayer during the transition stage between the MoS 2 and WS 2 monolayer growth. In contrast, isolated MoS 2 /WS 2 heterostructures with single WS 2 domain can be obtained with introducing the H 2 flow due to the reduced nucleation centers on the bottom MoS 2 monolayer arising from the hydrogen etching effect. Both the two kinds of the vertical MoS 2 /WS 2 heterostructures feature high quality. The photodetectors based on the isolated MoS 2 /WS 2 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 MoS 2 /WS 2 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.