Thermoluminescence Studies of Proton-Irradiated Cr-, Mg-Codoped β-Ga₂O₃

Chromium-doped Ga₂O₃, with intense Cr³⁺-related red-infrared light emission, is a promising semiconductor material for optical sensors. This work constitutes a comprehensive study of the thermoluminescence properties of Cr-, Mg-codoped β-Ga₂O₃ single crystals, both prior to and after proton irradiation. The thermoluminescence investigation includes a thorough analysis of measurements with different β^- irradiation doses used to populate the trap levels, with preheating steps to disentangle overlapping peaks (T_M-T_STOP and initial rise methods) and finally by computationally fitting to a theoretical expression. At least three traps with activation energies of 0.84, 1.0, and 1.1 eV were detected. By comparison with literature reports, they can be assigned to different defect complexes involving oxygen vacancies and/or common contaminants/dopants. Interestingly, the thermoluminescence signal is enhanced by the proton irradiation while the type of traps is maintained. Finally, the pristine glow curve was recovered on the irradiated samples after an annealing step at 923 K for 10 s. These results contribute to a better understanding of the defect levels in Cr-, Mg-codoped β-Ga₂O₃ and show that electrons released from these traps lead to Cr³⁺-related light emission that can be exploited in dosimetry applications.