The frequency response of the MOSFET inverted channel is analyzed by a transmission-line model. In this model, the interface traps are included and the minority carriers are assumed to follow the surface-potential variation. The channel frequency-response is characterized by two time constants (τl and τGC). The conductance Gl and capacitance C1 calculated from the minority-carrier current in the channel is used to determine τI and τGC from a frequency scan. Theoretical C1(V) and G1(V) curves are calculated and are in good agreement with experiments. The effect of high electrical field stressing is shown to increase both τI and τGC and thereby enlarge the frequency dispersion of the MOSFET admittances in inversion. The degradation in the channel frequency-response is more severe at lower inversion biases, where the degradation of mobility and the increase of interface-trap concentration are both more significant. The maximum of the G1(V) curve is very sensitive to the mobility and interface-trap concentration and can be used to monitor the degradation of the MOSFET. The degradation of the channel response due to high-field stressing is shown to depend on the gate-oxide thickness.
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