Optical spectroscopy of impurity levels in GaAs

Optical spectroscopy of impurity levels in GaAs is discussed with special emphasis on acceptors. Photoluminescence, Fourier transform infrared absorption, and electronic Raman scattering spectra are presented of shallow acceptors like carbon and zinc as well as of the 78/203 meV double acceptor. In the latter case Raman spectroscopy enables to analyse the electronic structure of the neutral double acceptor in detail and to determine the energy level diagram. Possible models for the microscopic structure of this double acceptor are reviewed including the Ga sub As antisite defect.