Backgating characteristics of MODFET structures

Significant backgating in mesa-isolated AlGaAs/GaAs MODFET structures is reported. Results are presented on the influence of backgate potential on the electrical characteristics of enhancement-mode MODFET's fabricated on MBE grown material. An observed zero threshold voltage for the onset of backgating is attributed to a high level of current leakage in the high-purity GaAs buffer layer. Transconductance and capacitance-voltage measurements on MODFET's show that the backgate potential influences primarily the electrical properties of the 2-D electron gas channel and the adjacent AlGaAs layer.