Shear-induced mechanical failure of β−Ga2O3 from quantum mechanics simulations

Abstract

Monoclinic gallium oxide ($\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$) has important applications in power devices and deep UV optoelectronic devices because of such novel properties as a wide band gap, high breakdown electric field, and a wide range of $n$-type doping conductivity. However, the intrinsic failure mechanisms of $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$ remain unknown, which limits the fabrication and packaging of $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$-based electronic devices. Here we used density-functional theory at the Perdew-Burke-Ernzerhof level to examine the shear-induced failure mechanisms of $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$ along various plausible slip systems. We found that the $(001)/\ensuremath{\langle}010\ensuremath{\rangle}$ slip system has the lowest ideal shear strength of 3.8 GPa among five plausible slip systems, suggesting that $(001)/\ensuremath{\langle}010\ensuremath{\rangle}$ is the most plausible activated slip system. This slip leads to an intrinsic failure mechanism arising from breaking the longest Ga\ensuremath{-}O bond between octahedral Ga and fourfold-coordinated O. Then we identified the same failure mechanism of $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$ under biaxial shear deformation that mimics indentation stress conditions. Finally, the general stacking fault energy (SFE) surface is calculated for the (001) surface from which we concluded that there is no intrinsic stacking fault structure for $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{G}{\mathrm{a}}_{2}{\mathrm{O}}_{3}$. The deformation modes and SFE calculations are essential to understand the intrinsic mechanical processes of this semiconductor material, which provides insightful guidance for designing high-performance semiconductor devices.