Novel channel materials for ballistic nanoscale MOSFETs-bandstructure effects

Performance limits of unstrained n- and p- MOSFETs with Si, Ge, GaAs and InAs channel materials are investigated using a 20 band sp³d⁵s*-SO semi-empirical atomistic tight-binding model and a top-of-the-barrier seminumerical ballistic transport model. It is observed that although the deeply scaled III-V devices offer very high electron injection velocities, their very low conduction band density-of-states strongly degrades their performance. Due to the high density-of-states for both electrons and holes in Ge, nanoscale devices with Ge as channel material are found to outperform all other materials considered