Atomic-scale theory on current-assisted thermochemical degradation mode and its field acceleration via charge trapping of O vacancy in HfSiO4

An atomic-scale model for current-assisted field-accelerated thermochemical degradation via charge capturing by O vacancy (V_O) is proposed based on first-principles calculations. We found that the electron current enhances the V_O formation around the V_O itself and the hole current makes the V_O transform into the puckered structure. The calculated activation enthalpy for breakdown and the effective dipole moment agree well with the experimental values. We also found that the subordinate carriers in the generated subordinate carrier injection (GSCI) model play critical roles through a disproportion reaction of positively charged V_Os.