  We consider the carrier transport and plasmonic phenomena in the lateral
carbon nanotube (CNT) networks forming the device channel with asymmetric
electrodes. One electrode is the Ohmic contact to the CNT network and the
another contact is the Schottky contact. These structures can serve as
detectors of the terahertz (THz) radiation. We develop the device model for
response of the lateral CNT networks which comprise a mixture of randomly
oriented semiconductor CNTs (s-CNTs) and quasi-metal CNTs (m-CNTs). The
proposed model includes the concept of the two-dimensional plasmons in
relatively dense networks of randomly oriented CNTs (CNT "felt") and predicts
the detector responsivity spectral characteristics. The detection mechanism is
the rectification of the ac current due the nonlinearity of the Schottky
contact current-voltage characteristics under the conditions of a strong
enhancement of the potential drop at this contact associated with the plasmon
excitation. We demonstrate that the excitation of the two-dimensional plasmons
by incoming THz radiation the detector responsivity can induce sharp resonant
peaks of the detector responsivity at the signal frequencies corresponding to
the plasmonic resonances. The detector responsivity depends on the fractions of
the s- and m-CNTs. The burning of the near-contact regions of the m-CNTs or
destruction of these CNTs leads to a marked increase in the responsivity in
agreement with our experimental data. The resonant THz detectors with
sufficiently dense lateral CNT networks can compete and surpass other THz
detectors using plasmonic effects at room temperatures.

Mesoscale and Nanoscale Physics