Electron emission properties of a defect at ∼(Ec−0.23 eV) in impurity-free disordered n-GaAs

Abstract

We have used deep level transient spectroscopy to study the electric-field-enhanced electron emission rate from a defect S1 observed in impurity-free disordered n-GaAs. The field dependence of emission rate could be well described by the electron emission from a Gaussian potential well with ground energy state ∼0.25eV. The phonon-assisted tunneling model with a triangular barrier could also adequately fit our experimental data for a large localized quasi-stationary energy level of ∼0.57eV. Our modeling shows that a medium-range potential is associated with S1, showing it cannot be a point defect. The possible complex structure of S1 is discussed in terms of the arsenic antisite, AsGa, and the arsenic interstitial, Asi, based on our results and by drawing on the theoretical modeling of defects in nonstoichiometric (As-rich) GaAs.