Deformation and fracture behaviors of monocrystalline β-Ga2O3 characterized using indentation method and first-principles calculations

Beta-phase gallium oxide (β-Ga2O3) is a potential candidate due to its ultra-wide bandgap and physical and chemical stabilities. However, its deformation and fracture behaviors are not well revealed, hinder the development of their ultra-precision machining. In this work, the surface deformation and fracture behaviors of monocrystalline β-Ga2O3 (−201), (001) and (010) planes were systematically investigated using indentation methods and first-principles calculations. The results demonstrate that the (−201) plane has a relatively large critical load for elastic-plastic transition, and the (010) plane is most prone to fracture; the elastic modulus and hardness were obtained from the load-displacement curve and showed the obvious anisotropy. First-principles calculations reveal that the composition of the chemical bonds and the stacking structure between atomic layers are the key factors affecting the mechanical properties. Slip bands, cleavage cracks and sliding cracks were formed on the (−201) and (001) planes. Cleavage cracks and bulk fracture dominated the deformation mode of (010) plane. In addition, the phase transition from β-Ga2O3 to α-Ga2O3 was found in the (−201) and (001) planes. These results are essential for realizing the ultra-precision machining of monocrystalline β-Ga2O3 for device manufacturing.