Assessment of the (010) $\beta$-Ga${}_2$O${}_3$ Surface and Substrate Specification

Recent breakthroughs in bulk crystal growth of the thermodynamically stable beta phase of gallium oxide ($\beta$-Ga${}_2$O${}_3$) have led to the commercialization of large-area beta-Ga${}_2$O${}_3$ substrates with subsequent epitaxy on (010) substrates producing high-quality films. Still, metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and processing of the (010) $\beta$-Ga${}_2$O${}_3$ surface are known to form sub-nanometer scale facets along the [001] direction as well as larger ridges with features perpendicular to the [001] direction. A density function theory calculation of the (010) surface shows an ordering of the surface as a sub-nanometer-scale feature along the [001] direction. Additionally, the general crystal structure of $\beta$-Ga${}_2$O${}_3$ is presented and recommendations are presented for standardizing (010) substrates to account for and control the larger-scale ridge formation.