Molybdenum and Tungsten Di-sulfides: First Principles Investigation of Adatom Attachment and Diffusion on c-plane Alpha Sapphire and Correlation with Growth

Understanding the underlying mechanism to growth of a material greatly assists control over its synthesis. In this investigation, we employ density functional theory to calculate the desorption and diffusion energy barriers to growth of MoS2 and WS2 from a M-C-O-H-S system on c-plane alpha sapphire, a commonly used substrate. We then perform experiments and use these numbers within a nucleation theory framework to explain growth characteristics. Nucleation rates, densities, and step velocities are predicted and analyzed. In particular, differences between MoS2 and WS2 growth -larger nucleation densities and small island sizes in WS2 compared to MoS2-are explained and correlated to the differences between energy barriers to desorption and diffusion of W and Mo.

Automated summary

This study uses density functional theory to investigate the growth mechanism of MoS2 and WS2 on α-sapphire substrate, and explains the growth characteristics and differences between MoS2 and WS2 growth by performing experiments and using nucleation theory framework.