  Theoretical description of the field emission of electrons from nanoscale
objects weakly coupled to the cathode is presented. It is shown that the field-
emission current increases in a step-like fashion due to single-electron
charging which leads to abrupt changes of the effective electric field
responsible for the field emission. A detailed consideration of the
current-voltage characteristics is carried out for a nanocluster modelled by a
metallic spherical particle in the close vicinity of the cathode and for a
cylindrical silicon nanowire grown on the cathode surface.
