The anisotropy of deformation behaviors in (100) and (010) plane of monoclinic β-Ga2O3 single crystals

β-Ga2O3 is an ultrawide bandgap (UWBG) semiconductor with excellent ensemble of attributes. To optimize the machining technologies and improve the mechanical performances, the plastic deformation mechanism of β-Ga2O3 is necessary to thoroughly understand. In this work, nanoindentation experiments were conducted on (100) and (010) oriented β-Ga2O3 to study the incipient plasticity with small indentation depths. It is indicated that the yield strength, elastic modulus and hardness for the (100) plane are higher than those of the (010) plane. Observations in the deformation morphology confirms that the deformed zone of the (100) plane is constrained in a hemispherical volume below the indentation with a radius about ten times larger than the indentation depth. However, for the (010) plane, a "one dimensional" plastic zone is formed in front of the tip with near one hundred times deeper than the penetration depth of the indenter. The deformation behavior is dominated by stacking faults, twins and dislocations for the (100) plane, while only dislocations are responsible for the plastic deformation of the (010) plane.