Abstract: In this study, using density functional theory and the SIESTA computational
code, we investigate the electronic and optical properties of the armchair graphene
nanoribbons and the armchair boron nitride nanoribbons of width 25 in the presence of a
transverse external electric field. We have observed that in the absence of the electric
field, these structures are semiconductors with a direct energy band at Γ point and
applying electric field on them causes to change in the band structure, increasing the
band gap and even eliminating the band gap. Increasing the intensity of the applying
field on the graphene nanoribbons reduces the distance between the maximum of the
highest valence band and the minimum of the lowest conduction band and shifts the
convergence of these two bands in K space from the Γ point to the X point. The energy
band gap of the boron nitride nanoribbons also has been decreased from 4.46 eV to less
than 32.6 meV in presence of a transverse electric field of intensity about 0.30 V/Ang
and a semiconductor-metal transition was observed in the presence of the stronger
fields.
Next, we investigate the effect of the transverse electric field on the optical properties
of both nanoribbons. Of course, in order to study the optical behavior of these systems,
we apply only a radiation with the parallel polarization. According to the changes that
the electric field makes on the band structure, we observed changes in the location and
intensity of the optical graphs peaks. Also with increasing the intensity of the field, we
observe a significant increase in the static dielectric constant and the plasmonic
behavior of these structures. پرونده مقاله