Effects of electron irradiation and thermal annealing on characteristics of semi-insulating gallium-arsenide alpha-particle detectors

Schottky diode nuclear radiation detectors based on semi-insulating gallium-arsenide (GaAs) wafers were fabricated. The minimum leakage current and current density of the detectors were 7.8 nA and 2.5 × 10−7 A/cm2, respectively, at a reverse bias of 100 V. The Schottky GaAs detectors were subjected to 10 MeV electron irradiation with a radiation dose of 0 to 200 kGy. Pre- and post-irradiation detectors were characterized by current–voltage, charge collection efficiency (CCE), and alpha-particle pulse-height spectroscopy. The detection efficiency of all detectors improved after irradiation, which may be attributed to defects induced by high-energy electron irradiation increasing the inhomogeneity of semi-insulating GaAs wafers. However, the energy resolution and CCE of the post-irradiation detectors decreased. After electron irradiation, the post-irradiation detectors were annealed at 200 °C for 5 min in nitrogen. The CCE of the annealed detectors improved, which suggests that the damages caused by high-dose electron irradiation can be repaired partially by annealing at 200 °C.