Hole mobility increase in ultra-narrow Si channels under strong (110) surface confinement

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We report on the hole mobility of ultra-narrow [110] Si channels as a function of the confinement length scale. We employing atomistic bandstructure calculations and linearized Boltzmann transport approach. The phonon-limited mobility of holes in thin [110] channels can be improved by more than 3X as the thickness of the (110) confining surface is reduced down to 3nm. This behavior originates from confinement induced bandstructure changes that decrease the hole effective mass and the scattering rates. Our results provide explanations for recent mobility measurements in nanobelts of similar dimensions.