ABSTRACT
A systematic experimental investigation of the influence of charge modulation on transport phenomena in pseudomorphic AlxGa1−xAs/InyGa1−y-As/GaAs field effect transistors as a function of In mole fraction (y) in the channel is presented. There is evidence that improved charge modulation can totally account for increases in both effective electron velocity and low-field drift mobility with increasing y. Transistor performance was observed to improve by 30% for y=0.25, in comparison to the conventional Al0.3Ga0.7As/GaAs HEMT. A state-of-the-art measured fT of 120 GHz was achieved with an fmax of 200 GHz for y=0.25 with a 0.18 μm gate length.
