Emission rate dependence on the electric field for two trap levels in proton-irradiated n -type GaAs

The electron emission rate dependence on the electric field for two levels in proton bombarded n-type GaAs, E1 and E2, was measured at different temperatures. E1 shows an emission enhancement completely described by the phonon-assisted tunneling model. The behavior observed for E2 is described by the sum of a Poole-Frenkel part and a phonon-assisted tunneling contribution. These data support a +/0/- charge state model for VAs in GaAs, and the potential contribution of this defect to the implant isolation process is discussed.