Structure, kinetics, and vibrational properties of complexes formed by hydrogen and gallium vacancies in GaAs: A theoretical study

In the last years, complexes formed by atomic H and gallium vacancies (V-Ga) have been investigated in order to account for donor-acceptor bands observed in the photoluminescence spectra of hydrogenated GaAs. New configurations for these complexes are investigated here, together with the kinetic properties of the H donors that affect the complex stability critically. In addition to the H donor, a peculiar V-Ga-H complex has been shown to behave as a donor. The electronic levels in the energy gap and several H vibrational modes have been studied for the new and the old configurations of the H-V-Ga complexes, as well as for the new donor. The new complexes are more stable than those previously studied and can well account for the photoluminescence results. The values of the H vibrational frequencies are quite different for the different types of complexes, which should permit a determination of the microstructure of the H-V-Ga complexes by infrared spectroscopy.