Threshold Voltage and Sub-Threshold Slope Variation with Gate-Length in Al<sub>2</sub>O<sub>3</sub>/InAlAs/InGaAs Quantum Well (QW) FET's

Abstract

We have theoretically examined the scaling of the Al2O3/InAlAs/InGaAs QW FET one of the proposed III-V channel MOSFET's designed to replace the conventional SiO2/Si structures. To accomplish this we have used a Schroedinger – Poisson – Continuity equation model that is fully 2-dimentional ie all equations are solved along and perpendicular to the channel. We have found out that for the threshold voltage VT to be around zero volts a Schottky barrier ΦΒ of 3.5 - 4.0eV is necessary. Both Cu or W will suffice. for this. The VT value moves by 0.7 as the device is scaled from 65 nm gate length Lg to 25nm. Furthermore, as the Lg is scaled to the desired 20nm value the subthreshold slope SS increases from 90meV/dec to about 170meV/dec guaranteeing fast switching.