Electronic properties of B-C-N ternary kagome lattices

We investigate the electronic properties of boron-carbon-nitrogen (B-C-N) analogues of a recently proposed carbon kagome lattice [Chen et al., Phys. Rev. Lett. 113, 085501 (2014)]. The B-C-N kagome lattices are constructed by replacing the carbon zigzag chains of the carbon kagome lattice with boron nitride zigzag chains. We use calculations of phonon dispersion curves to demonstrate the thermodynamic stabilities of the BCN and BC4N kagome lattices. The B-C-N kagome lattices are wide-band gap semiconductors although the band gaps of the BCN and BC4N kagome lattices are increased and reduced, respectively, compared with the carbon case. The reduction of the band gap is found to be caused by a direct to indirect gap transition in the BC4N kagome lattice.