[17a-F206-1~13] 13.3 Insulator technology

▲ [17a-F206-10] Valency of cation rather than Oxygen Density may govern the Dipole Moment at high-k/SiO₂ interfaces

〇(M1)Marc Perea¹, Okuto Takahashi¹, Koki Nakane¹, Nobuhiro Nagasawa¹, Takanobu Watanabe¹ (1.Waseda University)

Keywords:high-k dielectric, dipole formation, oxide

We show that the electric dipole formed at the high-k/SiO₂ interface is highly correlated to the mean valence number of the high-k cations. Molecular Dynamics (MD) simulations were performed, building high-k/SiO₂ interfaces for around 1300 Al, Mg, Sr and Ti based multi-component oxides, including Al₂O₃, MgO, SrO and TiO₂, which serve as easily identifiable references. The dipole moment of each oxide is plotted against both the normalized oxygen density (NOD, normalized around that of SiO₂) and the mean valence number of the oxide’s cations. Out of the two, the mean valence number of cations shows the higher correlation coefficient by a significant margin. At the same time, the normalized oxygen density plot shows unexpected results, according to the oxygen density difference accommodation model. These results suggest that, instead of the migration of oxygen ions, the migration of metal cations plays a huge factor in the formation of the dipole layer in high-k/SiO₂ interfaces.