Evaluating of MODFET gate capacitance and current gain cutoff frequency

In this paper, new analytical expressions have been derived setting the relation among channel carrier capacitance c/sub 2D/, sheet density carriers n/sub s/, gate bias v/sub G/, intrinsic parameters of semiconductor layers, and device´s geometry. The dependence of both, n/sub s/ and c/sub 2D/ on inverse gate polarisation has been compared with literature values. The influence of donor doping concentration N/sub D/ to characteristics n/sub s/ (v/sub G/) and c/sub 2D/(v/sub G/) has been investigated by the suggested analytical model. Also, the current-gain cutoff frequency f/sub t/ has been calculated for a short channel MODFET. The discrepancy between the calculated f/sub t/ and literature value has been discussed.