Investigation of transport phenomena in pseudomorphic MODFETs

A systematic experimental investigation of the influence of charge modulation on transport phenomena in pseudomorphic AlsubxGasub1minusxAs/InsubyGasub1minusyAs/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 equal 0.25, in comparison to the conventional Alsub0.3Gasub0.7As/GaAs HEMT. A state- of-the-art measured fsubT of 120 GHz was achieved with an fsubmax of 200 GHz for y equal 0.25 with a 0.18 Mym gate length.