Point Defects and Nanogrooves in β-Ga2O3: Formation Mechanisms and Effects on Optoelectronic and Gas-Sensing Applications

β-Ga2O3 crystal, a cutting-edge ultrawide bandgap semiconductor material, holds immense potential in ultraviolet optoelectronic, high-power, and gas-sensing devices. However, defects and impurities can significantly impact the performance of the β-Ga2O3-based devices. In the present study, a comprehensive analysis of the underlying specific impact and formation mechanism of β-Ga2O3 point defects was carried out based on density functional theory. The band structures, density of states, formation energy, and optical absorption of 20 types of point defects have been analyzed using the HSE06 functional and GGA-1/2+U method. Moreover, the composite mode of hydrogen interstitial and gallium vacancy was identified, which demonstrated that the impact of VGa on the optical properties can be reduced by hydrogen passivation. Oxygen vacancies can significantly improve the adsorption performance of NO2, NO, O2, and CO2 on the surface of β-Ga2O3. The melting back of twins and slip defects on the (100) plane may be responsible for nanogrooves in the [001] direction. Detailed information about the structures and formation energies of these twins and slip defects that tend to cause nanogrooves have been revealed. This study provides valuable insights for future research into β-Ga2O3 defects and applications.