  We have performed theoretical and experimental studies of field emission from
nanostructured semiconductor cathodes. Resonant tunneling through
electric-field-induced interface bound states is found to strongly affect the
field-emission characteristics. Our analytical theory predicts power-law and
Lorentzian-shaped current-voltage curves for resonant-tunneling field emission
from three-dimensional substrates and two-dimensional accumulation layers,
respectively. These predicted line shapes are observed in field emission
characteristics from self-assembled silicon nanostructures. A simple model
describes formation of an accumulation layer and of the resonant level in these
systems.
