Role of Ga and In adatoms in the epitaxial growth of β−Ga2O3

Abstract

The growth rate and crystal quality of $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ thin films are limited by suboxide (${\mathrm{Ga}}_{2}\mathrm{O}$) desorption. It has been reported that the growth of $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ by molecular beam epitaxy and metalorganic chemical vapor deposition can be improved by an additional indium supply. In order to reveal the mechanism by which In impacts growth, we use density functional theory to explore the adsorption of Ga and In adatoms on the ${\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$(010) surface and the effect of In on the growth rate. We find that the most stable configuration under an extreme Ga-rich condition is the surface with four Ga adatoms per unit cell. In the presence of indium, Ga adatoms become more strongly bound to the surface. Coadsorption of In and Ga thus increases the stability of the metal-covered surface and suppresses suboxide desorption; this explains the higher growth rate under Ga and In flux in experiments.