Charge transfer between EL2 and a trigonal Ga antisite-related acceptor in semi-insulating GaAs studied by optically detected magnetic resonance

Optical absorption and optically detected magnetic resonance in highly compensated undoped semi-insulating GaAs have been used to study the charge transfer processes between EL2 and an intrinsic trigonal acceptor (TA) pair defect during the photoquenching and thermal recovery of the EL2 defect. The concentrations of the TA acceptors are determined to be at least of the order of . One of its ionization levels is between the two ionization levels of EL2, i.e. 0.54 and 0.76 eV respectively above the valence band. It is concluded that the TA is a deep acceptor which plays an important role in the compensation mechanism of undoped semi-insulating GaAs.