  Spin-based metal-oxide-semiconductor field-effect transistors (MOSFET) with a
high-mobility III-V channel are studied using self-consistent quantum corrected
ensemble Monte Carlo device simulations of charge and spin transport. The
simulations including spin-orbit coupling mechanisms (Dresselhaus and Rashba
coupling) examine the electron spin transport in the 25 nm gate length
In$_{0.7}$Ga$_{0.3}$As MOSFET. The transistor lateral dimensions (the gate
length, the source-to-gate, and the gate-to-drain spacers) are increased to
investigate the spin-dependent drain current modulation induced by the gate
from room temperature of 300 K down to 77 K. This modulation increases with
increasing temperature due to increased Rashba coupling. Finally, an increase
of up to 20 nm in the gate length, source-to-gate, or the gate-to-drain spacers
increases the spin polarization and enhances the spin-dependent drain current
modulation at the drain due to polarization-refocusing effects.
