Irradiation-induced defects inp-type GaAs

Electron irradiation at room temperature in p-type vapor-phase-epitaxy-grown GaAs produces a series of traps labeled H0, H1, H2, H3, H4, and H5 situated at, respectively, 0.06, 0.25, 0.42, 0.54, 0.79, and 0.85 eV above the valence-band maximum Eᵥ. Their introduction rates as a function of the energy of irradiation and their annealing behavior have been studied using deep-level transient spectroscopy. From a comparison of the introduction rate and the annealing kinetics of H1 with electron traps produced by irradiation in n-type material, we deduced that this trap is associated with the arsenic vacancy-interstitial pair. The other traps (H2, H3, H4, and H5) are complexes of impurities with the arsenic interstitial, IAs, due to the fact that IAs is mobile under irradiation. From the annealing kinetics of these defects we deduce the activation energy associated with the IAs mobility (0.5±{}0.15 eV) in p-type GaAs. Finally, we also demonstrate that the E traps situated at 0.045, 0.140, 0.30 eV below the conduction-band minimum (labeled E1, E2, E3, respectively) present in electron-irradiated n-type GaAs are also present in p-type material and we have verified that these defects have the thermal stability expected from studies in n-type GaAs, i.e., associated with the charge-state effect.