MIS tunnel admittance with an inhomogeneous dielectric

A suitable equivalent circuit which incorporates the losses in the oxide layer of MIS tunnel structures is presented. The frequency dependence of the forward capacitance–voltage and conductance–voltage characteristics also are investigated while taking into account the parallel impedance attributed to the insulating layer. In fact, the latter is included in the model as a conductance in parallel with a capacitance, the contribution of which can be subtracted from the crudely measured data. The admittance expression of an ideal MIS tunnel diode can be readily derived as a special case from the more general proposed relations. The effect of the oxide conductance on the overall structure capacitance is shown to be appreciable at low frequencies. The effect is such that the capacitance falls rapidly as the frequency decreases, whereas the conductance increases with frequency in the low frequency limit.