Interface barriers at the interfaces of polar GaAs(111) faces with Al ₂O ₃

Internal photoemission measurements of barriers for electrons at interfaces between GaAs(111) and atomic-layer deposited Al ₂O ₃ indicate that changing the GaAs polar crystal face orientation from the Ga-terminated (111)A to the As-terminated (111)B has no effect on the barrier height and remains the same as at the non-polar GaAs(100)/Al ₂O ₃ interface. Moreover, the presence of native oxide on GaAs(111) or passivation of this surface with sulphur also have no measurable influence on the GaAs(111)/Al ₂O ₃ barrier. These results suggest that the orientation and composition-sensitive surface dipoles conventionally observed at GaAs surfaces are effectively compensated at GaAs/oxide interfaces.