Electron energy barriers at interfaces of GaAs(100) with LaAlO_3 and Gd_2O_3

摘要

Electron energy barriers at the interfaces of GaAs(100) with Gd_2O_3 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±0.1 eV for GaAs(100)/Gd_2O_3 is close to that measured at the GaAs(100)/LaAlO_3 interface which is consistent with the 5.8 and 5.7 eV wide band gaps of these two insulators. However, the defects revealed by photoionization measurements exhibit a distinctly different in-depth distribution. In GaAs/LaAlO_3 most of the traps are located close to the semiconductor surface, while in GaAs/Gd_2O_3 case they are found distributed across the entire oxide layer.