Backgating in GaAs/(Al,Ga)As modulation-doped field-effect transistors and its reduction with a superlattice

Abstract

Backgating in GaAs/(Al, Ga)As modulation-doped field-effect transistors was investigated experimentally and theoretically. The backgating transconductance varied linearly with buffer layer thickness for thicknesses of 1–3 μm. Incoporation of a thin superlattice at the substrate-epi interface reduced the backgating by about 20%. A model consistent with these findings was developed by treating the substrate potential and buffer layer background doping as a perturbation which raises or lowers the subband energies in the potential well containing the two-dimension electron gas.