  We report the observation of channel-width dependent enhancement in nanoscale
field effect transistors containing lithographically-patterned silicon
nanowires as the conduction channel. These devices behave as conventional
metal-oxide-semiconductor field-effect transistors in reverse source drain
bias. Reduction of nanowire width below 200 nm leads to dramatic change in the
threshold voltage. Due to increased surface-to-volume ratio, these devices show
higher transconductance per unit width at smaller width. Our devices with
nanoscale channel width demonstrate extreme sensitivity to surface field
profile, and therefore can be used as logic elements in computation and as
ultrasensitive sensors of surface-charge in chemical and biological species.
