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 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.

Recent Progress in Anisotropic 2D Semiconductors: From Material Properties to Photoelectric Detection

“…Space‐confined chemical vapor deposition (SC CVD) is an extended technique of chemical vapor deposition. [ 81–84 ] The schematic diagram of the reaction device for the growth of ReS 2 by the space‐confined vapor deposition is shown in Figure 3c. [ 80 ] The quartz boat with the precursor is placed in the middle of the glass tube.…”

The Photodetectors Based on Lateral Monolayer MoS2/WS2 Heterojunctions

“…In terms of crystal lattice quality, MoX 2 /WX 2 (X = S, Se or Te) lateral heterojunctions could induce structural defects scarcely due to their similar honeycomb-like [ 33 , 34 ] configuration and lattice parameters [ 34 ]. In addition, this kind of heterojunction can form type-II band alignment generally, which is desirable for high-efficiency photodetection [ 32 , 34 , 35 ].…”

“…Vertical heterostructures can be prepared by mechanical transfer and stack, whereas lateral ones can be only achieved by growth methods [ 14 ]. Furthermore, vertical heterostructures, as previously reported, cannot be precise control and it is easily contaminated at the interfaces between layers [ 33 ]. Luckily, the lateral heterostructures can be synthesized by one-step method to reduce contaminations [ 28 ].…”

Edge-Trimmed Nanogaps in 2D Materials for Robust, Scalable, and Tunable Lateral Tunnel Junctions

“…A potential solution to these challenges lies in the recent discovery of 2D materials [15][16][17][18]. These atomically thin materials have shown the ability to produce high-quality lateral junctions due to their highly stable and inherently sharp edges [15][16][17][18][19][20].…”