Irradiation-induced defects in p-type GaAs.

Abstract

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 ${E}_{v}$. 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, ${I}_{\mathrm{As}}$, due to the fact that ${I}_{\mathrm{As}}$ is mobile under irradiation. From the annealing kinetics of these defects we deduce the activation energy associated with the ${I}_{\mathrm{As}}$ mobility (0.5\ifmmode\pm\else\textpm\fi{}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.