Temperature effects on anisotropic mechanical properties of cast-grown β-Ga2O3

Abstract

The production and application of beta-phase gallium oxide (β-Ga2O3) single crystals—an emerging ultrawide bandgap semiconductor—is frequently coupled with high temperature and mechanical load. Understanding the anisotropic mechanical properties at high temperature is crucial for optimizing the production and application of high-performance β-Ga2O3, enhancing its stability and reliability in high-temperature environments. Selective nanoindentation is conducted on unintentional-doped (100)-grown β-Ga2O3 wafers at both room temperature (RT) and a high temperature (HT) of 600 °C, by aligning one facet of the Berkovich indenter parallel to either [001] or [010] low-index directions in the (100) surface. The [010] direction exhibits higher Young's modulus (E) and lower hardness (H) compared to the [001] direction at RT. The deformation morphology confirmed that the deformed zones were localized under the [001] direction while more homogeneously distributed under the [010] direction. Under HT, both E and H decreased to different extents in both directions, where anisotropic deformation mechanisms were noted. These findings can provide guidance for ultra-precision machining and HT applications of monocrystalline β-Ga2O3.