Carrier-concentration-dependent low-filed-mobility model for InAlAs/InGaAs/InP lattice-matched HEMT for microwave application

A carrier-concentration-dependent low-field-mobility model for a lattice-ma tched InAlAs/InGaAs/InP HEMT for microwave frequency applications is develo ped. The dependence of mobility on carrier concentration affects the curren t-voltage characteristics, and also the gate-voltage dependence of transcon ductance. An approximation for the two-dimensional electron gas (2-DEG) con centration versus the gate-to-channel voltage, which models both the subthr eshold region and the gradual saturation of carriers, due to the onset of c harge modulation, has been used. The model also evaluates the cutoff freque ncy as a function of gate length, and a value of 203 GHz is obtained. (C) 2 001 John Wiley & Sons, Inc.