posted on 2021-04-23, 14:38authored byPeng Shao, Li-Ping Ding, Feng Ding
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.