Molecular dynamics study on the formation of dipole layer at high-k/SiO₂ interfaces

We show that electric dipole layer at Al₂O₃/SiO ₂ interface is reproduced by classical molecular dynamics simulation with a simple two-body rigid ion model. The dipole layer was spontaneously formed by the migration of oxygen ions from Al₂O₃ side to SiO₂ side. Built-in potential at the Al₂O ₃/SiO₂ is estimated to about 0.35V, which roughly compares with the experimental value of the flat band voltage shift. Contrary, no significant dipole layer appeared at Y₂O₃/SiO₂ interface. The simulation results are explained in terms of the difference in the magnitude of multipole moments around cations of these oxides.