  A charge carrier confined in a quasi-one-dimensional semiconductor helical
nanostructure in the presence of an electric field normal to the axis of the
helix is subjected to a periodic potential proportional to the strength of the
field and the helix radius. As a result, electronic properties of such
nanohelices are similar to those of semiconductor superlattices with parameters
controlled by the applied field. These properties include Bragg scattering of
charge carriers by a periodic potential, which results in energy gap opening at
the edge of the superlattice Brillouin zone. This provides an opportunity for
creating a new class of tunable high-frequency devices based on semiconductor
nanohelices.
