  We investigate effect of a step-doping profile on the spin injection from a
ferromagnetic metal contact into a semiconductor quantum well (QW) in spin FETs
using a Monte Carlo model. The considered scheme uses a heavily doped layer at
the metal/semiconductor interface to vary the Schottky barrier shape and
enhance the tunneling current. It is found that spin flux (spin current
density) is enhanced proportionally to the total current, and the variation of
current spin polarization does not exceed 20%.
