  Bias-induced light emission and thermal radiation from conducting channels of
carbon nanotubes (CNTs) with defects are studied theoretically within the
framework of nonequilibrium Green's function method based on a tight-binding
model. Localized states induced by the single vacancy defect and single
Stone-Wales defect in the low energy range enhance electroluminescence
significantly while they reduce thermal radiation under zero bias. The
influence of the diameters of the CNTs with defects on the radiation is
discussed. Different from the 2D or bulk materials, the radiation intensities
from quasi-one-dimensional metallic CNTs in thermal equilibrium are much
smaller than that of the black-body radiation. We attribute this to the
confinement of thermal excitation in the transverse direction of the CNT. Our
study is important for optoelectronic applications of CNTs with defects.
