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

TL;DR

This study demonstrates that using an $ ext{α}$-Cr$_2$O$_3$ buffer layer during HVPE growth on sapphire substrates produces phase-pure $ ext{α}$-Ga$_2$O$_3$ films with significantly reduced dislocation densities, improving film quality.

Contribution

It introduces a method of using an $ ext{α}$-Cr$_2$O$_3$ buffer layer to achieve phase-pure $ ext{α}$-Ga$_2$O$_3$ films with lower dislocation densities compared to growth on bare sapphire.

Findings

Phase-pure $ ext{α}$-Ga$_2$O$_3$ achieved with buffer layer.

Dislocation density reduced by four times with buffer layer.

Growth on bare sapphire results in mixed phases and higher dislocation density.

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$^{-2}$.