HYDROGENATING AND ANNEALING EFFECTS OF GAAS

Photoluminescence (PL) and photoreflectance (PR) measurements on a nom inally undoped GaAs layer grown by molecular beam epitaxy have been ca rried out to investigate the neutralization of the carbons and the var iation of the charges in the GaAs. After the GaAs was hydrogenated and annealed at 400-degrees-C, PL measurements showed that the relative i ntensity ratio between the donor-bound exciton and the carbon acceptor increased by a factor of 2. PR measurements indicate that the variati on of the broadening parameter is induced by a neutralization of the c arbon acceptors. These results were caused by the neutralization of th e carbon due to the combination of the hydrogenic ions and the carbon ions in the GaAs or by the separation of the hydrogen atoms resulting from the thermal treatment.