A new interpretation of the channel charge control mechanism in GaAs MESFET's

Experimental results are given to illustrate the drawbacks of the classical theory for the channel pinch-off mechanism in GaAs MESFET's. The peak electron concentration in the nearly pinched off MESFET channel is found to vary more slowly than predicted by Shockley's theory and as a result, a drastic decrease in the gate capacitance is observed in the near pinch-off regime. A new theoretical model based on the concept of overall charge neutrality is proposed and is shown to be in excellent agreement with the measured data.