New configuration-coordinate model for the ground, excited, and metastable states ofEL2in GaAs

A new configuration-coordinate model for EL2, where the excited state has asymmetrical dual minima, is proposed to explain the oscillatory spectrum of transition rate obtained by a novel spectral photocapacitance transient analysis measurement. The model claims that an electron in the excited state of EL2 has a probability of relaxing both to the conduction band and to the metastable state. It can explain a Gaussian shape of the photoquenching spectrum which cannot be interpreted with the conventional scheme. The proposed model suggests that EL2 in GaAs originates from a complex defect of arsenic antisite with arsenic interstitial atom(s).