Degradation mechanism in carbon-doped GaAs minority-carrier injection devices [HBTs]

Degradation behavior and mechanism of GaAs-based devices under minority-carrier injection has been studied by measuring the increase in the leakage current and the luminescence lifetime of minority carriers. It is found that hydrogen unintentionally incorporated in GaAs-based devices induces degradation under minority-carrier injection, i.e., increase in injection leakage current at low bias voltage. “Isolated” hydrogen donors (H⁺) induce rapid degradation, and even carbon-hydrogen (C-H) complexes which are believed to be electrically neutral induce slow degradation. Degradation is induced by the decomposition of the C-H complexes, enhanced by minority-carrier injection producing electrically active isolated hydrogen donors (H⁺). The kinetics of the leakage current increase are well explained by the decomposition kinetics of the C-H complexes. Under minority-carrier injection, H⁺ changes to hydrogen acceptors (H^- ) by capturing two electrons. Hydrogen donors (H⁺) and hydrogen acceptors (H^-) combine and become a molecular hydrogen which Is thought to form {111} platelets. This decomposition mechanism are not due to recombination-enhanced defect reaction (REDR) but is related to charge state effects by two-electron capturing. We infer that the degradation mechanism is closely related to the leakage through the {111} platelets