Hole mobility enhancements in strained In_xGa_1-xSb heterostructure p-channel MOSFETs

We explore the use of strain and heterostructure design based on physical modeling to enhance the hole mobility in ultrathin body In_xGa_1-xSbbased p-channel MOSFETs. The band structure under quantum confinement is calculated by solving the six-band k · p Schrödinger and Poisson equations self-consistently. Hole mobility is modeled by the Kubo-Greenwood formula accounting for acoustic and optical phonons, polar optical phonons, surface roughness, and alloy scattering mechanisms. Physical models are calibrated with experimental data. Our results suggest that hole mobility in In_xGa_1-xSb-based devices increases with increasing InSb mole fraction x, especially under biaxial compressive strain. Mobility markedly deteriorates with the scaling down of body thickness in both unstrained and strained cases. Moreover, an insert of a very thin cap layer with a wide bandgap is helpful to enhance hole mobility. Therefore, greater mobility enhancements are achieved by strained heterostructure optimization.