Theoretical investigations of a new two-dimensional semiconducting boron-carbon-nitrogen structure

A new two-dimensional boron-carbon-nitrogen (BCN) structure is predicted and is theoretically investigated based on density functional theory. The BCN structure belongs to the space group C222, and is composed of twelve B, twelve C and twelve N atoms per orthorhombic cell (named oC-B₁₂C₁₂N₁₂). It consists of small hollow spheres with two hexagons per sphere. The dynamical, thermal and mechanical stabilities of oC-B₁₂C₁₂N₁₂ are respectively evaluated by phonon spectroscopy, ab initio molecular dynamics calculations and elastic constant measurements. The simulated in-plane stiffness and Poisson ratio display anisotropic features. The band structure shows that oC-B₁₂C₁₂N₁₂ is a direct semiconductor with a gap of 2.72 eV (GW). oC-B₁₂C₁₂N₁₂ has an absorption range from the visible light spectrum to the ultraviolet. Therefore, due to its small direct band gap and optical absorption, oC-B₁₂C₁₂N₁₂ may be a good candidate for electronic and optical applications.