Investigation of Hole Mobility in Strained InSb Ultrathin Body pMOSFETs

Hole mobility in strained ultrathin body InSb-on-insulator (InSb-OI) devices is calculated by a microscopic approach. The anisotropic valence band structures, in consideration of quantum confinement, are obtained via solving the six-band k· p Schrödinger and Poisson equations self-consistently. Hole mobility is calculated using the Kubo-Greenwood formula accounting for nonpolar acoustic and optical phonons, polar optical phonons, and surface roughness scatterings. The models are calibrated and verified with experimental data. The influences of body thickness and strain effect, including both biaxial and uniaxial strains, are investigated in InSb-OI devices. Our results indicate that mobility degradation occurs in both single-gate (SG) and double-gate (DG) mode when body thickness scales down below a certain range. Moreover, mobility in the DG mode outperforms that in the SG for thick body thickness, but loses its superiority over SG for extremely thin body. Compressive strain is favorable to hole mobility. Furthermore, more enhancement is achieved by uniaxial strain than biaxial strain.