A method to electronically modulate the energy gap and band-structure of
semiconducting carbon nanotubes is proposed. Results show that the energy
gap of a semiconducting nanotube can be narrowed when the nanotube is
placed in an electric field perpendicular to the tube axis. Such effect
in turn causes changes in electrical conductivity and radiation
absorption characteristics that can be used in applications such as
switches, transistors, photodetectors and polaron generation. By applying
electric fields across the nanotube at a number of locations, a
corresponding number of quantum wells are formed adjacent to one another.
Such configuration is useful for Bragg reflectors, lasers and quantum
computing.