  High frequency conductivity of hot electrons in an undoped single walled
achiral carbon nanotubes (CNTs) under the influence of ac-dc driven fields is
considered. We investigated semiclassically by solving the Boltzmann's
transport equation with and without the presence of the hot electrons source to
derive the current densities. Plots of the normalized current density versus
frequency of ac-field reveal an increase in both the minimum and maximum peaks
of normalized current density at lower frequencies as a result of a strong
enough injection of hot electrons . The applied ac-field plays twofold role of
suppressing the space-charge instability in CNT and simultaneously pumping an
energy for lower frequency generation and amplification of THz radiations which
have enormous promising applications in very different areas of science and
technology.
