  Using density functional theory calculations, we have examined the structural
stability, electronic, magnetic and optical properties of rectangular shaped
quantum dots (QDs) of graphene (G), Boron Nitride (BN) and their hybrids.
Different hybrid QDs have been considered by substituting a GQD (BNQD) with
BN-pairs (carbon atoms) at different positions. Several parameters like size,
amount of substitution etc. have been varied for all these QDs (GQDs, BNQDs,
hybrid-QDs) to monitor the corresponding changes in their properties. Among the
considered parameters, we find that substitution can act as a powerful tool to
attain interesting properties with these QDs, for example, broad range of
absorption (~2000 nm) in the near infrared (NIR) region, spin-polarized
HOMO-LUMO gaps without the application of any external-bias etc., which are
highly required in the preparation of opto-electronic, electronic/spintronic
devices etc. Explanations have been given in details by varying different
factors, like, changing the position and amount of substitution, application of
external electric-field etc., to ensure the reliability of our results.
