Electronic Structure of Boron Flat Holeless Sheet

Abstract

The electronic band structure, namely energy band surfaces and densities-of-states (DoS), of a hypothetical flat and ideally perfect, i.e., without any type of holes, boron sheet with a triangular network is calculated within a quasi-classical approach. It is shown to have metallic properties as is expected for most of the possible structural modifications of boron sheets. The Fermi curve of the boron flat sheet is found to be consisted of 6 parts of 3 closed curves, which can be approximated by ellipses representing the quadric energy-dispersion of the conduction electrons. The effective mass of electrons at the Fermi level in a boron flat sheet is found to be too small compared with the free electron mass m 0 and to be highly anisotropic. Its values distinctly differ in directions Γ–K and Γ–M: m Γ – K / m 0 ≈ 0.480 and m Γ – M / m 0 ≈ 0.052 , respectively. The low effective mass of conduction electrons, m σ / m 0 ≈ 0.094 , indicates their high mobility and, hence, high conductivity of the boron sheet. The effects of buckling/puckering and the presence of hexagonal or other type of holes expected in real boron sheets can be considered as perturbations of the obtained electronic structure and theoretically taken into account as effects of higher order.