Electron Mobility Behavior of Ge-Free Ultrathin-Body (UTB) Strained-SOI (sSOI) MOSFETs

The electron mobility and the channel thickness dependences of ultrathin-body (UTB) strained silicon-on-insulator (sSOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) were investigated. Ultrathin silicon channels less than 10 nm in thickness were formed by defect-free wet etching. Both UTB-sSOI MOSFETs and UTB-SOI MOSFETs revealed superior subthreshold swing. The electron mobility of the UTB-sSOI MOSFETs was larger than that of the UTB-SOI MOSFETs. However, the enhanced mobility of the UTB sSOI-MOSFETs was not observed for channel thicknesses less than 10 nm. The monotonic decrease of the electron mobility is related to the inter-valley phonon scattering and variation in the channel-thickness scattering caused by the quantum confinement effect.