Estimation of insulation layer conductance in MNOS structure

A method for estimating the conductance of each insulation layer of MNOS devices is described. In this method, the conductance values can be independently estimated using the frequency dependence of the capacitance and conductance versus gate voltage characteristics. The frequency dependence in the accumulation region can be explained by an equivalent circuit which considers the substrate resistance and the conductance of each insulation layer. It was found that the conduction processes in nitride and oxide layers are dominated by Frenkel-Poole emission and direct tunnelling emission, respectively, and that the degradation of retention characteristics of MNOS memory devices with erase/write cycles is caused by increased nitride conductance