Electric Dipole at High-k/SiO2 Interface and Physical Origin by Dielectric Contact Induced Gap States

The characteristic of electric dipole at high-k/SiO2 interface is quantitatively analyzed. The dipoles of HfO2/SiO2 and HfGdOx/SiO2 systems are experimentally estimated to be about -0.38 and -1.03 V, respectively. The dipole formation is explained by the dielectric contact induced gap states (DCIGS). The charge neutrality level (CNL) of the DCIGS is for the first time utilized to study the dipole moment. The charge transfer due to different CNLs of high-k and SiO2 is considered to be the dominant origin of dipole formation. The prediction by this model is in good agreement with the experimental data.