Mechanism of MoS2 Growth on a Au(111) Surface: An Ab Initio Molecular Dynamics Study

Abstract

Chemical vapor deposition (CVD) of transition-metal dichalcogenide (TMD) thin films, such as MoS2, on a gold (Au) surface has been regarded as one of the most promising approaches for the mass production of high-quality TMD thin films. However, the mechanism of TMD CVD growth on a gold surface remains a mystery, and many experimental observations, such as the surface chemistry during the initial stage of TMD growth and the formation of T-phase MoS2 on a Au surface, remain unclear. In this study, we systematically explored the initial stage of MoS2CVD growth on a Au(111) surface by using density functional theory-based molecular dynamics simulations. Some critical steps of MoS2 growth, such as the sulfidation of MoO3, the passivation of the Au(111) surface in the S-rich environment, and the lifting of Mo atoms from the Au substrate to form stable MoS2 nuclei, have been revealed in our atomic simulations. The theoretically predicted most stable T-phase small MoS2 clusters agree well with the previous experimental observations. Therefore, with an increase in the size of MoS2, a phase transition from the T phase to the H phase is essential for the growth of highly stable H-phase MoS2 films. This study greatly deepens our understanding of the mechanism of TMD CVD growth on a Au surface and provides guidance for the controllable CVD synthesis of various TMDs.