  We report the observation of Coulomb blockade in field electron emission (FE)
from single-wall carbon nanotubes (SWCNTs), which is manifested as pronounced
steps in the FE current-voltage curves and oscillatory variations in the energy
distribution of emitted electrons. The appearance of the Coulomb blockade is
explained by the formation of nanoscale protrusions at the apexes of SWCNTs due
to the electric field-assisted surface diffusion of adsorbates and carbon
adatoms. The proposed adsorbate-assisted FE mechanism is substantially
different from the well-known resonant tunneling associated with discrete
electronic states of adsorbed atoms. The simulations based on the Coulomb
blockade theory are in excellent agreement with the experimental results. The
SWCNT field emitters controlled by the Coulomb blockade effect are expected to
be used to develop on-demand coherent single-electron sources for advanced
vacuum nanoelectronic devices.
