  Silicon metal-oxide-semiconductor field effect transistors (MOSFETs)
fabricated on a SIMOX (001) substrate, which is a kind of silicon on insulator
(SOI) substrate, that is annealed at high temperature for a long time are known
to exhibit large valley splitting, but the origin of this splitting has long
been unknown. Extended zone effective-mass approximation (EMA) predicts that
strain significantly affects valley splitting. In this study, we analyzed
valley splitting based on this theory and found that the shear strain along
<110> of approximately 5% near the buried oxide (BOX) interface is a promising
source for large valley splitting.
