  The Hanle-type spin precession method was carried out associated with
non-local magnetoresistance measurement using a highly doped (5\times10^19)
silicon channel. The spin diffusion length obtained by the Hanle-method is in
good agreement with that by the gap dependence of non-local signals. We have
evaluated the interface and bulk channel effects separately, and it was
demonstrated that the major source of temperature dependence of non-local
signals originates from the spin polarization reduction at interface between
the tunnel barrier and silicon.
