Bandstructure Effects in Ultra-Thin-Body DGFET: A Fullband Analysis

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.