Physical Strategies for Geometric Control of Transition Metal Dichalcogenide Atomic Layers by Chemical Vapor Deposition

The diverse morphologies of 2D transition metal dichalcogenides (2D TMDs) motivate their broad potential applications in the next generation of electronic, optical, and catalytic technologies. It is advantageous to develop controllable growth techniques that afford versatility through direct manipulation of the growth parameters. A fundamental understanding of the physical mechanisms driving various growth modes is crucial for achieving the process precision necessary for obtaining reproducible morphologies in 2D TMDs. Thermodynamic and kinetic considerations are two key physical strategies. Thermodynamic strategies mainly involve the manipulation of parameters like temperature and the chemical potential of precursors to ensure the thermostability of various morphologies. Conversely, kinetic strategies, focusing on the factors, like precursor diffusion, adsorption, and desorption during the growth, also enable atomic-level kinetics control of the resulting morphologies. Often, an interplay of both mechanisms drives the growth of a particular morphology. This review aims to provide an updated guidance for exploiting these physical strategies in the versatile technique of chemical vapor deposition. The opportunities for further exploring the control of these physical mechanisms are discussed through recent examples with an eye on unlocking the untapped potential of 2D TMDs in areas such as phase engineering and shape control for advanced applications.