First-principles study of the structural, electronic, and optical properties of Ga 2 O 3 in its monoclinic and hexagonal phases

We report the results of a comprehensive study on the structural, electronic, and optical properties of ${\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ in its ambient, monoclinic $(\ensuremath{\beta})$ and high-pressure, hexagonal $(\ensuremath{\alpha})$ phases in the framework of all-electron density functional theory. In both phases, the conduction band minimum is at the zone center while the valance band maximum is rather flat in the $k$ space. The calculated electron effective mass ${m}_{e}^{*}∕{m}_{0}$ comes out to be 0.342 and 0.276 for $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ and $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$, respectively. The dynamic…