Electron mobility characteristics of n-channel metal-oxide-semiconductor field-effect transistors fabricated on Ge-rich single- and dual-channel SiGe heterostructures

An investigation of electron mobility characteristics in single-, dual-, and digital-alloy channel n-MOSFETs grown on Ge-rich virtual substrates is presented. In the single-channel case, it is found that mobility enhancements ranging from 1.4 to 1.6 times could be attained, despite incomplete confinement of the wave function or defect scattering. In the dual-channel case, it is found that for h_{Si cap}=7.5 nm, the presence of the buried Ge layer does not significantly affect electron mobility, because the type-II conduction band offset and large out-of-plane effective mass allow electrons to b confined in the ℰ-Si cap.