Optimisation of modulation-doped heterostructures for TEGFET operation at room temperature

Abstract

Optimisation of selectively doped (AlGa)As/GaAs heterostructures for TEGFET applications at room temperature is reported. The introduction of a thick (>0.1 μm) highly doped GaAs top layer considerably reduces parasitic resistances and improves device performance. Best results for 1.4 μm gate length at room temperature are: transconductance 220 mS/mm; source resistance 0.2–0.4 mm; contact resistance less than 0.1 Ω mm and cutoff frequency 25 GHz. Results from comparable structures without a thick top layer are inferior by about 25%.