Anisotropic phonon response to electron irradiation in <b> <i>β</i> </b> -Ga2O3 single crystals revealed by temperature-dependent Raman spectroscopy

Abstract

The β-phase of gallium oxide (β-Ga2O3) is an ultrawide bandgap semiconductor with excellent electrical properties and strong radiation tolerance, making it a promising candidate for electronic devices operating in harsh radiation environments. However, the monoclinic symmetry of β-Ga2O3 dictates highly anisotropic lattice dynamics, yet how electron irradiation-induced defects perturb these phonons along different crystallographic orientations remains experimentally unexplored. Herein, temperature-dependent Raman spectroscopy was employed to investigate the phonon responses of the (100) and (2¯01) planes of β-Ga2O3 single crystals under electron irradiation with an energy of 10 MeV and total fluence of 1 × 1017 cm−2. The results show that irradiation significantly reduces Raman peak intensities and induces distinct orientation-dependent frequency shifts. The (100) plane exhibits blue shifts in low- and mid-frequency modes but red shifts in high-frequency modes, whereas the (2¯01) plane shows nearly unchanged peak positions, indicating that the (2¯01) plane possesses higher radiation resistance. Furthermore, the irradiation-induced variation in first-order temperature coefficients is considerably larger for the (100) plane, revealing stronger phonon anharmonicity and phonon-defect interactions. This work provides insights into the orientation-dependent phonon dynamics of β-Ga2O3 under irradiation and guidance for the design of radiation-hardened β-Ga2O3-based electronic and thermal management devices.