  The electronic, thermal and optical properties of a monolayer BeO with Boron
(B) and Nitrogen (N) co-dopant atoms are studied by means of a density
functional theory computation. Our calculations reveal that BeO with
BN-codopant atoms can give rise to more effective and outstanding performance
for the thermal and optical responses. More significantly, the monolayer BeO
with BN codopant atoms becomes a semiconductor with a direct band gap in
comparison with the insulator behavior of pristine BeO. The particular
attention of this work is paid to the influence of the atomic configuration and
the interaction of the B and N dopant atoms with BeO. The interaction of the B
and N atoms with the BeO monolayer diminishes degenerate energy states forming
flat bands. It is also found that there is a strong attractive interaction
between the O and N atoms forming a strong sigma bond breaking the symmetry of
BeO structure. Consequently, the band gap is reduced leading to a semiconductor
behavior with improved thermoelectric properties such as the Seebeck
coefficient and the figure of merit. The reduced band gap and the flat bands
induce a high optical responses such as the refractive index, the reflectivity
and the optical conductivity in the visible light region. In addition, the
anisotropy of a monolayer BeO with B and N atoms regarding different direction
of electromagnetic polarization is presented. We anticipate that our results
can be useful for design of both thermoelectric and optoelectronic devices.
