Energy barriers at interfaces of (100)GaAs with atomic layer deposited Al₂O₃ and HfO₂

Band alignment at the interfaces of (100)GaAs with Al₂O ₃ and HfO₂ grown using atomic layer deposition is determined using internal photoemission and photoconductivity measurements. Though the inferred conduction and valence band offsets for both insulators were found to be close to or larger than 2 eV, the interlayer grown by concomitant oxidation of GaAs reduces the barrier for electrons by approximately 1 eV. The latter may pose significant problems associated with electron injection from GaAs into the oxide.