HVPE growth of corundum-structured $\alpha$-Ga$_2$O$_3$ on sapphire substrates with $\alpha$-Cr$_2$O$_3$ buffer layer

Abstract

Gallium oxide films were grown by HVPE on (0001) sapphire substrates with and without $\alpha$-Cr$_2$O$_3$ buffer produced by RF magnetron sputtering. Deposition on bare sapphire substrates resulted in a mixture of $\alpha$-Ga$_2$O$_3$ and $\epsilon$-Ga$_2$O$_3$ phases with a dislocation density of about $2\cdot10^{10}$ cm$^{-2}$. The insertion of $\alpha$-Ga$_2$O$_3$ buffer layers resulted in phase-pure $\alpha$-Ga$_2$O$_3$ films and a fourfold reduction of the dislocation density to $5 \cdot 10^9$ cm$^{-2}$.