Experimental evidence of increased deformation potential at MOS interface and its impact on characteristics of ETSOI FETs

Deformation potential (D
_ac
), which determines the strength of electron-phonon scattering, is one of the most important physical parameters of Si. A longstanding unresolved question in D
_ac
is that D
_ac
for MOSFETs is considered to be much greater than D
_ac
for bulk Si. In this work, we have demonstrated for the first time that D
_ac
increases sharply at MOS interfaces within several-nm range. Because of the enhanced D
_ac
at MOS interface, D
_ac
for nanoscale SOI channel is expected to be increased owing to the high surface-to-volume ratio, which is verified by electron mobility calculations in extremely-thin SOI (ETSOI) MOSFETs and experimental stress-induced mobility enhancement in nanoscale SOI.