  One-dimensional (1D) sub-bands in cylindrical InAs nanowires (NWs) are
electrically mapped as a function of NW diameter in the range of 15-35 nm. At
low temperatures, stepwise current increases with the gate voltage are clearly
observed and attributed to the electron transport through individual 1D
sub-bands. The two-fold degeneracy in certain sub-band energies predicted by
simulation due to structural symmetry is experimentally observed for the first
time. The experimentally obtained sub-band energies match the simulated
results, shedding light on both the energies of the sub-bands as well as the
number of sub-bands populated per given gate voltage and diameter. This work
serves to provide better insight into the electrical transport behavior of 1D
semiconductors.
