Unveiling Defect Dynamics in Gallium Oxide: In-Situ TEM Insights under Ion Irradiation and Annealing.

Gallium oxide (GaO) is distinguished in the electronics field for its ultrawide bandgap, high breakdown field, and transparency to visible and infrared light, making it highly attractive for sensor applications in harsh environments. This study investigates the evolution of defects in GaO under ion irradiation, annealing, and their combined effects, with a unique focus on in situ transmission electron microscopy (TEM) observations. We examined three electron-transparent GaO lamellas (samples A, B, and C) under distinct conditions: Sample A was subjected to Kr ion irradiation up to 15.4 displacements per atom (dpa) at room temperature; Sample B was annealed in 100 °C increments up to 500 °C; Sample C underwent simultaneous annealing at 500 °C and ion irradiation. TEM provided detailed, real-time characterization throughout the experiments, offering unprecedented insights into defect dynamics. Our findings reveal the formation and growth of small black defects (SBDs), defect clusters, and dense dislocation networks under irradiation. The crystal structure remained stable during gradual heating, but combined irradiation and temperature effects accelerated defect formation and evolution. Notably, a phase transition from β to γ was observed during the irradiation-only experiment. The in situ and ex-situ TEM observations provide a novel and impactful perspective on the behavior of GaO, contributing significantly to the understanding of its properties under extreme conditions. These insights pave the way for the development of more resilient GaO electronic devices, enhancing their performance and reliability in demanding applications.