Abstract:
The van der Waals interaction-corrected density functional theory is used in
this study to investigate the formation, energetic stability, and inter-layer cohesion in
bilayer hexagonal boronitrene. The effect of inter-layer separation on the electronic
structure is systematically investigated. The formation and energetic stability of
intrinsic defects are also investigated at the equilibrium inter-layer separation. It is
found that nonstoichiometric defects, and their complexes, that induce excess nitrogen
or excess boron, in each case, are relatively more stable in the atmosphere that
corresponds to the excess atomic species. The modifications of the electronic structure
due to formation of complexes are also investigated. It is shown that van der Waals
density functional theory gives an improved description of the cohesive properties but
not the electronic structure in bilayer boronitrene compared to other functionals. We
identify energetically favourable topological defects that retain the energy gap in the
electronic structure, and discuss their implications for band gap engineering in low-n
layer boronitrene insulators. The relative strengths and weaknesses of the functionals
in predicting the properties of bilayer boronitrene are also discussed.
