Determination of carrier saturation velocity in high-performance InyGa1-yAs/AlxGa1-xAs modulation-doped field-effect transistors (0 ≤ y ≤ 0.2)

We describe a new method for determining the carrier saturation velocity υsatin modulation-doped field-effect transistors (MODFET's). High-performance pseudomorphic InyGA1-yAs/AlGaAs MODFET's (0 ≤ y ≤ 0.20) grown by MBE were tested, and the dependence of υsaton InAs mole fraction y was obtained. It was found that each device with y > 0 had a higher υsatthan a conventional GaAs/ AIGaAs MODFET (y = 0). Further, we believe that there is an optimum InAs mole fraction such that υsatis maximized. A pseudomorphic MODFET structure optimizing υsatmay also optimize overall device performance.