Contact-related deep states in the Al-GaInP/GaAs interface

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Abstract
Deep levels have been measured in a 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 a Schottky contact. A contact‐related hole trap with an activation energy of 0.50–0.75 eV was observed at the Al/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 oxygen contamination, or a vacancy‐related defect, VIn or VGa. A new electron trap at 0.28 eV was also observed in both Au‐ and Al‐Schottky diodes. It depth profile showed that it is a bulk trap in a GaInP epilayer. The temperature dependent current‐voltage characteristics show a large interface recombination current at the GaInP surface due to the Al contact. The energy distribution of the interface state density showed a maximum at EV+0.85 eV within the band gap. 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 aluminum deposition. The Al Schottky barrier height also increased after a 450 °C annealing.