BACKGATING IN SUBMICROMETER GAAS-MESFET OPERATED AT HIGH DRAIN BIAS

GaAs 0.8-mu-m MESFET's are shown to exhibit an increased sensitivity to backgating when operated at drain voltages above 3.5 V. This is accompanied by an abrupt increase in the dc output conductance (kink effect) and an increase in the current flowing in the back-gate electrode. It is proposed that the increased sensitivity to backgating is due to the injection of holes, from the high-field region of the channel, into the semi-insulating substrate. The results suggest that conventional layout rules may not always be sufficient to avoid backgating in circuits based in submicrometer GaAs MESFET's.