  This paper discusses a few unique effects of ultra-thin-body double-gate
NMOSFET that are arising from the bandstructure of the thin film Si channel.
The bandstructure has been calculated using 10-orbital $sp^3d^5s^*$
tight-binding method. A number of intrinsic properties including band gap,
density of states, intrinsic carrier concentration and parabolic effective mass
have been derived from the calculated bandstructure. The spatial distributions
of intrinsic carrier concentration and $<100>$ effective mass, arising from the
wavefunction of different contributing subbands are analyzed. A self-consistent
solution of Poisson-Schrodinger coupled equation is obtained taking the full
bandstructure into account, which is then applied to an insightful analysis of
volume inversion. The spatial distribution of carriers over the channel of a
DGFET has been calculated and its effects on effective mass and channel
capacitance are discussed.
