Atomistic-Level Modeling for Thickness Dependence of Electron Mobility in InSb QW-FETs

The thickness dependence of electron mobility in the InSb quantum well (QW) FETs are calculated based on an atomistic approach for bandstructure calculation. The electron effective mass (m*) is computed using fast yet accurate sp³d⁵s* tight-binding (TB) method for InSb quantum-well (QW) (or ultra-thin-body, UTB) with thickness of 3-16 nm. The m* dependence on the UTB thickness is then used in determining the electron mobility in the channel region of InSb QW-FETs. It is found that in QW-FETs, optical phonon scattering is a dominant factor, which is in turn strongly coupled to the carrier effective mass determined by channel thickness. The thickness dependence of electron mobility differs from that of the MOSFETs, where surface roughness is one of the major scattering mechanisms