Hole mobility and device characteristics of SiGe dual channel structure

Hole mobility and current–voltage characteristics of p-type MOS transistors with dual channel are examined. High hole mobility needs high Ge compositions in channels (higher than 60% Ge). Besides, hole mobility in alloy channels does not seem much degraded by alloy scattering. Even though high hole mobility could be easily obtained for dual channels with higher than 60% Ge, junction leakage and subthreshold characteristics are severely worsened. These results indicate that there should be a tradeoff between mobility enhancement and the threshold characteristics of p-type MOS transistors for adopting the SiGe dual channel with high Ge composition.