【Other Papers】Multimodal optical positron characterization of radiation-induced defects and their evolution in β-Ga₂O₃

      Researchers from North Carolina State University have published a dissertation titled " Multimodal optical positron characterization of radiation-induced defects and their evolution in β-Ga₂O₃ " in Journal of Materials Science.

Abstract

      Gallium oxide (Ga₂O₃) is an emerging candidate for next-generation radiation detectors due to its ultrawide bandgap, high-temperature stability, and large breakdown field, making its radiation tolerance and defect behavior critical to advancing device performance. To investigate the mechanisms of radiation damage and microstructural evolution, β-Ga₂O₃ samples were irradiated at the North Carolina State University PULSTAR reactor to neutron fluences up to ~10¹⁸ cm⁻² at both room temperature and 700 °C using custom vertical irradiation ports that enable continuous exposure while allowing selective retrieval of samples at predetermined dose levels. Post-irradiation characterization using optical transmittance measurements and positron annihilation spectroscopy (PAS) revealed pronounced radiation darkening and reduced transmittance in room-temperature-irradiated samples, accompanied by increased positron lifetimes indicative of progressive defect accumulation. In contrast, samples irradiated at 700 °C exhibited minimal optical darkening and negligible changes in positron lifetime, suggesting that elevated temperature suppresses the formation or retention of neutron-induced defects. These results highlight a thermal threshold that strongly governs defect diffusion, recombination, and trapping behavior in β-Ga₂O₃, providing insight into pathways for enhancing its radiation resilience for nuclear and high-energy applications.

DOI：

https://doi.org/10.1007/s10853-026-13696-7