  Temperature-dependent I-V and C-V spectroscopy of single InAs nanowire
field-effect transistors were utilized to directly shed light on the intrinsic
electron transport properties as a function of nanowire radius. From C-V
characterizations, the densities of thermally-activated fixed charges and trap
states on the surface of untreated (i.e., without any surface
functionalization) nanowires are investigated while enabling the accurate
measurement of the gate oxide capacitance; therefore, leading to the direct
assessment of the field-effect mobility for electrons. The field-effect
mobility is found to monotonically decrease as the radius is reduced to sub-10
nm, with the low temperature transport data clearly highlighting the drastic
impact of the surface roughness scattering on the mobility degradation for
miniaturized nanowires. More generally, the approach presented here may serve
as a versatile and powerful platform for in-depth characterization of
nanoscale, electronic materials.
