Contact-Related Deep States in AI-GaInP/GaAs Interface

Abstract

AbstractDeep levels have been measured in molecular beam epitaxy grown Ga0.51In0.49P/GaAs heterostructure by double correlation deep level transient spectroscopy. Gold(Au) and Aluminum (Al) metals were used for Schottky contact. A contact-related hole trap with an activation energy of 0.50-0.75eV was observed at the A1/GaInP interface, but not at the Au/GaInP interface. To our knowledge, this contact-related trap has not been reported before. We attribute this trap to the oxygen contamination, or a vacancy-related defect, VIn or VGa. A new electron trap at 0.28eV was also observed in both Au- and Al-Schottky diodes. Its depth profile showed that it is a bulk trap in GaInP epilayer. The temperature dependent current-voltage characteristics (I-V-T) show a large interface recombination current at the GaInP surface due to the Al-contact. Concentration of the interface trap and the magnitude of recombination current are both reduced by a rapid thermal annealing at/or above 450°C after the aluminum deposition.