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

Abstract

We describe a new method for determining the carrier saturation velocity υ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</inf> in modulation-doped field-effect transistors (MODFET's). High-performance pseudomorphic In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</inf> GA <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-y</inf> As/AlGaAs MODFET's (0 ≤ y ≤ 0.20) grown by MBE were tested, and the dependence of υ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</inf> on InAs mole fraction y was obtained. It was found that each device with y > 0 had a higher υ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</inf> than a conventional GaAs/ AIGaAs MODFET (y = 0). Further, we believe that there is an optimum InAs mole fraction such that υ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</inf> is maximized. A pseudomorphic MODFET structure optimizing υ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</inf> may also optimize overall device performance.