Mobilty modeling of strained germanium (s-Ge) quantum well (QW) heterostructure pMOSFETs

In this work, we have performed a thorough study of the mobility in `Si / s-Ge / Si´ QW heterostructure pMOSFETs. We have been able to accurately fit experimental data obtained from ultra-thin strained-Ge QW FETs by theoretical calculations, in which the hole sub-band structure is calculated by 6×6 k.p Poisson-Schrodinger equation, and all the important scattering mechanisms (acoustic phonon, optical phonon, surface roughness and alloy scattering) are included. Through experiments and detailed simulations, the effects of the s-Ge quantum well (QW) thickness and quantum confinement effects on the hole mobility of both, single-gate (SG) and double-gate (DG) QW pMOSFETs are explored. Theoretical optimums of the device structure are obtained through simulations of the mobility, drive current and switching delay, in highly scaled s-Ge QW DG FETs (Lg=I5nm Ts=5nm).