Abstract
p-NiO/n-Ga(2)O(3) heterojunction (HJ) diodes exhibit much larger changes in their properties upon 1.1 MeV proton irradiation than Schottky diodes (SDs) prepared on the same material. In p-NiO/Ga(2)O(3) HJ diodes, the narrow region adjacent to the HJ boundary is found to contain a high density of relatively deep centers with levels near E(C)-0.17 eV and a depleted region in the immediate vicinity of the HJ boundary. The series resistance of the HJ diodes is slightly higher than for the Schottky diodes and shows a temperature dependence with activation energy ~ 0.12 eV, like the temperature dependence of the NiO film resistivity. Irradiation with 1.1 MeV protons leads to a decrease of the hole concentration in the NiO, with a high carrier removal rate of ~ 1.3 × 10(5) cm(-1) and a strong compensation of the interfacial region where the concentration of the E(C)-0.17 eV centers decreases with a high rate of ~ 7 × 10(3) cm(-1). The combined action of these two effects gives rise to the much stronger increase of the series resistance of the HJ diodes compared to Schottky diodes. The observed differences between the radiation response of the HJs and SDs cannot be credibly attributed to the changes of the density of any of the deep electron and hole traps detected in our experiments.