Chemical Vapor Deposition Growth of Two-Dimensional Compound Materials:Controllability,Material Quality,and Growth Mechanism

CONSPECTUS:Two-dimensional(2D)compound materials are regarded as promising candidates in many applications,including electronics,optoelectronics,sensors,and flexible devices,because they have high carrier mobility,tunable bandgaps,large specific surface area,atomic-level thickness,and cover lots of other properties.In order to bring 2D compound materials from the laboratory to industrial applications,materials preparation is the first prerequisite.Among all methods to prepare 2D compound materials,chemical vapor deposition(CVD)is one of the promising methods because it can grow a series of 2D compound materials with high quality as well as reasonable cost.So far,many efforts have been made in the CVD growth of 2D compound materials with large domain size,controllable number of layers,fast growth rate,and high-quality features,etc.Therefore,the CVD method has shown much potential for the commercialization of 2D compound materials.However,due to the complicated growth mechanism like sublimation and diffusion processes of multiple precursors,maintaining the controllability,repeatability,and high quality of CVD-grown 2D compound materials is still a big challenge,which prevents their widespread use.In this Account,taking 2D transition metal dichalcogenides(TMDCs)as examples,we review current progress and highlight some promising growth strategies for the CVD growth of 2D compound materials.In detail,the key technology parameters that affect the CVD process,including non-metal precursor,metal precursor,substrate engineering,temperature,and gas flow,are systematically discussed.In addition,we introduce some emerging methods in improving the quality of CVD-grown 2D compound materials(e.g.,repairing the sulfur vacancies by thiol chemistry).Then the current understanding of the CVD growth mechanism is summarized and discussed.In the end,we conclude the current challenges and propose the potential opportunities in this field in terms of the growth of novel 2D compound materials(e.g.,p-type materials,2D materials with high carrier mobility,2D materials with wide bandgaps in the ultraviolet regime or narrow bandgaps in the infrared regime,and 2D nonlayered materials),the post-treatment of CVD-grown samples to obtain new 2D materials and heterostructures,and the exploration of the exotic 2D physics and their promising applications.Overall,we believe this review will guide the future design of controllable CVD systems for the growth of 2D compound materials with good controllability and high quality,laying the foundations for their potential applications.