Investigation of the machinability of (001) single-crystal β-Ga2O3 via tribological methodology

Gallium oxide (Ga2O3) is a promising material for next-generation power devices due to its ultrawide bandgap and extremely high critical electric field strength; however, the strong anisotropy and cleavage tendency of Ga2O3 pose significant challenges for high-precision surface processing. In this work, a systematic study was conducted through tribological analysis of monocrystalline (001) β-Ga2O3. Initially, reciprocal sliding tests were conducted on β-Ga2O3 along different crystallographic directions, [100] and [010]. The results revealed that the [100] direction was more wear resistant, while the [010] direction was more prone to failure. Indentation experiments on (001) β-Ga2O3 showed extensive slip and cleavage cracking along different crystallographic orientations, indicating that mechanical wear might dominate the wear mode of this material. Subsequently, sliding tests under various environmental conditions revealed that the wear rate was correlated with humidity. Additionally, β-Ga2O3 exhibited time-dependent frictional behavior, with its coefficient of friction stabilizing around 0.1, 0.5, and 0.9 at different stages during the wear test. These findings indicate that the frictional behavior of Ga2O3 is closely linked to the state of its surface. This study provides critical insights into the tribological behavior of Ga2O3 and offers guidance for ultraprecision machining of this material.