Atomic Insights of Irradiation-Induced Thermal Conductivity Degradation in β-Ga 2 O 3

β-Ga 2 O 3 shows great potential for extreme-environment applications. However, its low thermal conductivity inevitably limits device reliability. Herein, the defect evolution and thermal conductivity degradation caused by irradiation along different β-Ga 2 O 3 orientations are systematically investigated by simulations and experimental verifications. The simulation results suggest that Ga vacancies, O interstitials, and Ga O antisite defects are the predominant defects after primary irradiation damage. Besides, a reordering of the anisotropic thermal conductivity after primary irradiation damage is observed, sequencing from κ ⊥(010) > κ ⊥(001) > κ ⊥(100) (before irradiation) to κ ⊥(010) > κ ⊥(100) > κ ⊥(001) (after irradiation). The experiments verify that the thermal conductivity of (100)-oriented β-Ga 2 O 3 is significantly reduced by 34.38% after irradiation with a 2.0 MeV electron beam at a total fluence of 1.0 × 10 17 cm –2 . This work clarifies the anisotropic degradation of thermal conductivity due to irradiation, providing atomic-level insights for optimizing the thermal transport properties in β-Ga 2 O 3 -based devices.