Electric field-induced carrier recovery and thermal stability of radiation-induced defects in β-Ga2O3

This study explores the effects of proton irradiation and post-irradiation carrier removal and recovery mechanisms on β-Ga2O3 Schottky diodes. Carrier recovery was achieved through voltage stressing and thermal annealing, providing insights into defect migration and carrier compensation. Voltage stressing at room temperature facilitated partial carrier recovery, while complete carrier recovery was achieved by annealing at 400 °C without applied voltage. Defect analysis, conducted using Deep Level Transient (Thermal)/Optical Spectroscopy (DLTS/DLOS), identified key irradiation-induced states at EC−0.34 eV, EC−0.6 eV, EC−0.7 eV, EC−1.2 eV, and EC−2.0 eV. Isochronal annealing from 200 to 400 °C revealed that the thermal activation energy to remove these traps individually ranged from 0.3 to 1.2 eV, with the EC−2.0 eV being the dominant compensating trap. A difference was observed between the concentration of removed carriers and the increase in trap concentration after irradiation, with the trap introduction rate lagging the carrier removal rate. While the mechanism of this additional carrier removal is not yet known and does not appear to be related to compensation by defects detected by DLTS and DLOS, the thermal recovery of these lost carriers is well characterized by a simple first-order reaction kinetics model, with a thermal activation energy of 1.0 ± 0.1 eV. Interestingly, this activation energy was found to be significantly dependent on the magnitude of the electric field present within the depletion region, decreasing to 0.13 eV at only 0.2 MV/cm at 305 K. This implies a major role for field-induced migration in the source of this carrier removal.