Unification of three multiphonon trap-assisted tunneling mechanisms

There are three basic multiphonon trap-assisted tunneling (TAT) mechanisms in the gate leakage current of a metal-oxide-semiconductor (MOS) structure: the short-ranged trap potential, nonadiabatic interaction and electric field induced trap-band transitions. In this paper, a comparison of these three mechanisms is made for the first time in a single (Schenk’s model) MOS structure. A properly box-normalized electron wave function in the SiO2 conduction band in an electric field is used to calculate the field ionization rate of a deep neutral trap. It is found that capture and emission rates of a deep neutral trap are almost the same in the short-ranged trap potential and nonadiabatic interaction induced TAT processes, so the two mechanisms give a similar contribution to the total TAT current. The calculated TAT current and the average relaxation energy (∼1.5 eV) due to these two mechanisms are in good agreement with the experimental results. In contrast, capture and emission rates in Schenk’s model are sev...