Through theoretical calculation, the phonon-limited electron mobility in fully depleted strained Si n-channel MOSFETs fabricated on silicon on insulator (i.e., sSOI) and SiGe on insulator (SGOI) was compared between the two structures as a function of Si thickness. In the Si thickness range from 10 nm down to 3 nm, the phonon-limited electron mobility in the sSOI n-MOSFET was about 1.5 times higher than that of a conventional SOI n-MOSFET. In particular, it was found that the electron mobility in the sSOI n-MOSFET was about 3% lower than that in the SGOI n-MOSFET. This difference can be attributed to two physical phenomena: first, that the sSOI n-MOSFET has higher inter-valley scattering rates than does the SGOI n-MOSFET, because of its greater carrier confinements: and second, that some electrons in the inversion layer of the SGOI n-MOSFET tunnel into the SiGe layer. These theoretical results are strongly consistent with previous experimental results.

Keywords: Strained Silicon, sSOI n-MOSFET, Ultra-thin Body, Electron Mobility Enhancement