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 H₂ flow on and off: MoS₂ /WS₂ heterostructures with multiple WS₂ domains can be achieved without introducing the H₂ 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 H₂ 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.

Luyao Huangfu

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