Electron energy barriers at interfaces of GaAs(100) with $LaAlO3$ and $Gd2O3$

Electron energy barriers at the interfaces of GaAs(100) with $Gd2O3$ appear to be insensitive to the Fermi level pinning indicating that charges at interface states are of marginal importance for the band alignment at semiconductor/insulator interfaces. The inferred conduction band offset of $1.6±0.1eV$ for $GaAs(100)∕Gd2O3$ is close to that measured at the $GaAs(100)∕LaAlO3$ interface which is consistent with the 5.8 and $5.7eV$ wide band gaps of these two insulators. However, the defects revealed by photoionization measurements exhibit a distinctly different in-depth distribution. In $GaAs∕LaAlO3$ most of the traps are located close to the semiconductor surface, while in $GaAs∕Gd2O3$ case they are found distributed across the entire oxide layer.