Study on Dipole Layer Formation between Two Oxides : Experimental Evidences and Possible Models

Abstract

ABSTRACTHetero-interface between two oxides sometimes forms a dipole layer which is experimentally observable macroscopically, as an electric potential barrier at the interface. Investigation of the flatband voltage shift of the metal-insulator-semiconductor capacitors with bilayer oxides as the insulator is suitable to characterize the dipole formation at the interface of two oxides. A model to explain the driving force to form the dipole is discussed by taking account of the areal density difference of oxygen atoms at the interface, which should be a guideline to predict both the direction and magnitude of the interface dipoles. Based on this model the requirement for the oxides to form the dipoles is also discussed.