Two‐Dimensional Metal Chalcogenide Heterostructures: Designed Growth and Emerging Novel Applications

Abstract

There has been a renewed interest in 2D metal chalcogenide heterostructures (2DMCHs) in the context of their exceptional optoelectronic properties and potential for a wide variety of practical applications. However, the controllable synthesis of 2DMCHs remains a huge challenge. Recently, chemical vapor deposition (CVD) has been proposed to be an efficient way to realize high‐quality, large‐scale, and layer‐controllable 2D materials and has also shown high feasibility in 2DMCHs. Here, the latest controllable CVD growth strategies of 2DMCHs are introduced. The designed growth techniques mainly focus on three vital factors in CVD: source supply, mass transport, and substrate engineering. Then, the emerging novel applications of 2DMCHs are also systematically reviewed with particular attention to memory, infrared photodetector, and moiré superlattice, which have demonstrated significant progress in recent years. Finally, future opportunities and remaining challenges concerning the developments of 2DMCHs are presented.

Synthesis of layered vs planar Mo2C: role of Mo diffusion

“…To comprehend the growth of two different crystals, it is important to understand the kinetics. Modiffusion limited growth mechanism is proposed where the competition between Mo and C adatoms along the edges and surfaces determines the morphology of grown crystals as explained in TMD growth [12,[32][33][34]. It is important to consider the difference in CVD growth schemes of TMDs and current sandwich approach.…”

Layer-Structured Anisotropic Metal Chalcogenides: Recent Advances in Synthesis, Modulation, and Applications

“…Epitaxial growth of vertical, lateral, and multijunction lateral heterostructures of different 2D MCs has been accomplished, including WSe 2 /MoSe 2 , WSe 2 /MoS 2 , MoSe 2 /WSe 2 , MoS 2 /WS 2 , ,, and NbS 2 /MoS 2 . Multiheterostructures (such as WS 2 –WSe 2 –MoS 2 and WS 2 –MoSe 2 –WSe 2 ) and superlattices or multiple alternating blocks (such as WS 2 –WSe 2 –WS 2 –WSe 2 –WS 2 ) have also been achieved recently using the multistep sequential CVD growth process . For sequential growth, the nucleating primary block (e.g., WS 2 ) was placed at the downstream end, and the powder source of the selected secondary block (WO 3 and Se for WSe 2 ) was heated for evaporation under the carrier gas (e.g., Ar) at the upstream end.…”

“…(g) Cross-sectional HAADF-STEM image and atomic-resolution HAADF-STEM image of the interface between the Bi 2 O 2 Se film and the STO substrate. (a) Reprinted with permission from ref . Copyright 2021 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.…”

“…183 have also been achieved recently using the multistep sequential CVD growth process. 552 For sequential growth, the nucleating primary block (e.g., WS 2 ) was placed at the downstream end, and the powder source of the selected secondary block (WO 3 and Se for WSe 2 ) was heated for evaporation under the carrier gas (e.g., Ar) at the upstream end. The edges of the primary block acted as a lateral epitaxy provider for continued lateral growth, whereas the basal plane acted as a vdW epitaxy provider for vertical heterostructure formation at the downstream end of the CVD furnace.…”