Tribological studies of $\alpha$-$\beta$-Ga$_{2}$O$_{3}$ layers paired with a sapphire counterface

The wear resistance of epitaxial layers of $\alpha$- and $\beta$-polymorphs of gallium oxide grown on sapphire substrates has been considered. This is one of the first studies of the tribological properties of a promising wideband semiconductor crystal. As a result of tribotests conducted with the participation of a sapphire counterface in the process of dry friction in air, it has been shown that the layers of a metastable $\alpha$-Ga$_{2}$O$_{3}$ are more resistant to abrasion than the layers of the thermostable $\beta$-phase. At the same time, the obtained values of the wear coefficients allow us to attribute both polymorphs to wear-resistant materials and especially $\alpha$-Ga$_{2}$O$_{3}$ with a corundum structure. In addition, $\alpha$- and $\beta$-Ga$_{2}$O$_{3}$ demonstrate extremely low values of friction coefficients: lower than those of sapphire.