Neutron irradiation effects in p-GaN

Abstract

Electrical properties, admittance, and microcathodoluminescence spectra are compared for p-GaN samples grown by hydride vapor phase epitaxy (HVPE) and by molecular beam epitaxy (MBE). The former are characterized by a high 300K hole concentration and a weak temperature dependence of conductivity. The latter samples show strongly temperature-activated conductivity due to ionization of Mg acceptors. The main effects of neutron irradiation were similar for the p-HVPE and the p-MBE materials: a compensation of p-type conductivity starting with neutron fluences exceeding 2×1016cm−2 and conversion to high resistivity n type with the Fermi level pinned near Ec-(0.8–0.9)eV after irradiation with high doses of 1018cm−2. For the heavily neutron irradiated p-HVPE samples, a strong increase was observed in the c-lattice parameter which indicates an important role for interstitial-type defects.