A first-principles study of low-energy radiation responses of β-Ga2O3

The degradation of β-Ga2O3-based devices’ performance may occur when they are bombarded by charged particles in aerospace, astronomy, and nuclear-related applications. It is significant to explore the influence of irradiation on the microstructure of β-Ga2O3 and to reveal the internal relationship between the damage mechanisms and physical characteristics. Thus, we explored the low-energy recoil events of β-Ga2O3 based on the first-principles calculations in the present study. The threshold displacement energies (Eds) significantly depended on the recoil directions and the primary knock-on atoms. Eds of Ga atoms are generally larger than those of O atoms, indicating that the displacements of O atoms dominate under electron irradiation. In the neutral state, the formation energy of VO(I) is lower than that of VO(II) and VO(III), while in the +2 charge state, the case is a reversal. The formation energy of Oint(II) defect is high, and thus its equilibrium concentration is low, indicating that the Oint(II) defect is unlikely to be relevant for the thermal-mechanical properties of β-Ga2O3. The charged VO and Oint defects deteriorate the ability to resist external compression more profoundly, while defective β-Ga2O3 with lower Young's modulus is expected to possess higher elastic compliance than pristine β-Ga2O3. The lattice thermal conductivity of β-Ga2O3 decreases with increasing temperature and the charged point defects generally result in the decreasing lattice thermal conductivity more profoundly than neutral point defects. The presented results provide underlying mechanisms for defect generation in β-Ga2O3 and advance the fundamental understanding of the radiation resistances of semiconductor materials.