Thermal recovery from the metastable state of deep lying defect level EL2 in GaAs investigated by piezoelectric photoacoustic technique

Thermal recovery of the photo-quenched metastable state of EL2 in semi-insulating GaAs is investigated by using a piezoelectric photoacoustic (PPA) technique from a non-radiative transition point of view. The isothermal annealing effect of the PPA signal from the quenched state shows that an activation energy of the recovery is 0.30eV. This energy is believed to represent the thermal barrier between metastable EL2* and conduction band. Usefulness of the PPA technique to investigate a non-radiative electron transition through the defect level is demonstrated.