Impact of indium mole fraction on the quantum transport of ultra-scaled In x Ga1–x As double-gate Schottky MOSFET: tight-binding approach

Abstract

This paper explores the impact of indium mole fraction on the electrical characteristic of InxGa1–xAs double-gate Schottky MOSFET (SBFET) in nanoscale regime. A 20-band sp3d5s* tight-binding formalism is applied to compute the bandstructure of ultra-thin body structure as a function of indium mole fraction. The injection velocity of carriers is increased as the indium mole fraction approaches to x = 1. Quantum confinement results in an increment of the effective Schottky barrier height especially for the increased values of indium mole fraction. The ultra-scaled InxGa1–xAs SBFET suffers from a low conduction band DOS in the Γ valley that results in serious degradation of the gate capacitance. The electrical characteristic of this device is considered by solving self-consistent 2D Schrődinger–Poisson equations based on non-equilibrium Green’s function formalism. For channel thicknesses where the effect of quantum confinement on the gate capacitance is not dominant, shrinking the channel thickness besides increasing the indium mole fraction improves the electrical characteristic of the device. However, for the ultra-scaled structure, the indium mole fraction enhancement degrades the device performance due to the enhanced value of Schottky barrier height and low DOS.