  The silicon (Si) based spin-MOSFET (metal-oxide semiconductor field-effect
transistor) is considered to be the building block of low-power-consumption
electronics, utilizing spin-degrees of freedom in semiconductor devices. In
this paper, we review the latest results on the spin transport in nanoscale
Si-based spin-valve devices, which is important to realize the nanoscale
spin-MOSFET. Our results demonstrate the importance of ballistic transport in
obtaining high spin-dependent output voltage in nanoscale Si spin-valve
devices.
