Correlation between the backgating effect of a GaAs MESFET and the compensation mechanism of a semi-insulating substrate

The backgating effect on FET'S fabricated both on a Cr-doped HB and on an undoped LEC substrate is investigated. The deep impurity compensation is found to influence the backgating effect both through the formation of the electric dipole layer at the interface between the n-channel and i-substrate, and through the voltage drop in the semi-insulating substrate.