LOW-FREQUENCY DISPERSION OF TRANSCONDUCTANCE IN GAAS JFETS AND MESFETS WITH AN ION-IMPLANTED CHANNEL LAYER

An analytical model of low-frequency dispersion of trans-conductance in GaAs FET’s which have nonuniform profiles of carrier concentration and mobility is reported. The frequency dependence of surface charge density is incorporated into the model as a variation in the source resistance of the FET’s. The model elucidates the low-frequency dispersion of transconductance in GaAs p-n junction FET’s (JFET’s) and metal-semiconductor FET’s (MESFET’s), both of which have a channel layer formed by ion implantation. It is suggested that the low-frequency dispersion of transconductance can be attributed to the charge exchange which occurs with the surface states in GaAS FET’s. © 1990 IEEE