Origin of electric dipoles formed at high-k/SiO2 interface

A model for the physical origin of the dipole formed at high-k/SiO2 interface is proposed. In our model, an areal density difference of oxygen atoms at high-k/SiO2 interface is considered as an intrinsic origin of the dipole formation. The oxygen movement from higher-oxygen-density side to a lower-oxygen-density one will determine the direction of interface dipole. The bonding energy relaxation at the interface explains why the oxygen density difference is the driving force of the oxygen movement. Our model enables the prediction of the dipole directions for candidate gate dielectrics, including those so far not reported.