Charge-state-controlled structural relaxation of theEL2center in GaAs

Existing approaches are unsuccessful in explaining the anomalous persistent photocapacitance quenching effect associated with the $\mathrm{EL}2$ center in GaAs. Here a model is presented which invokes a simple physical mechanism to account in a consistent way for all aspects of this behavior. The model consists of a charge-state-controlled, electrostatic and lattice-strain driven, structural rearrangement of a defect complex. This rearrangement results in two defect configurations, each with distinct electronic and optical properties. It is proposed that this type of configurational instability may be common, but rarely detected, in covalent semiconductors.