Abstract: Abstract: Hole mobility changes under uniaxial and combinational stress in different directions are characterized and analyzed by applying additive mechanical uniaxial stress to bulk Si and SiGe-virtual-substrate-induced strained-Si (s-Si) p-MOSFETs (metal-oxide-semiconductor field-effect transistors) along <110> and <110> channel directions. In bulk Si, a mobility enhancement peak is found under uniaxial compressive strain in the low vertical field. The combination of <110> direction uniaxial tensile strain and substrate-induced biaxial tensile strain provides a higher mobility relative to the <110> direction, opposite to the situation in bulk Si. But the combinational strain experiences a gain loss at high field, which means that uniaxial compressive strain may still be a better choice. The mobility enhancement of SiGe-induced strained p-MOSFETs along the <110> direction under additive uniaxial tension is explained by the competition between biaxial and shear stress.

Key words: hole mobility enhancement