Electronic properties and stability phase diagrams for cubic BN surfaces.

This contribution investigates structural and electronic properties as well as stability phase diagrams of surfaces of the cubic boron nitride (c-BN). Our calculated parameters for bulkc-BN agree reasonably well with both experimental and computed values available in the literature. Based on the energies of the three experimentally recognised phases of bulk boron, i.e.α-B36,β-B105andγ-B28, we estimate enthalpy of formation ofc-BN to be −2.8 eV. Thec-BN(1 0 0) surface offers separate B and N terminations (denoted asc-BN(1 0 0)_B and c-BN(1 0 0)_N), whereasc-BN(1 1 1) andc-BN(1 1 0) are truncated with combinations of boron and nitrogen atoms (denoted asc-BN(1 1 1)_BN andc-BN(1 1 0)_BN). Optimised geometries of surfaces display interlayer displacements up to the three topmost layers. Downward displacement of surface boron atoms signifies a common geometric feature of all surfaces. Bulkc-BN and its most stable surfacec-BN(1 0 0)_N possess no metallic character, with band gaps of 5.46 and 2.7 eV, respectively. We find that, onlyc-BN(1 0 0)_B configuration exhibits a metallic character.c-BN(1 1 0)_BN andc-BN(1 1 1)_BN surfaces display corresponding band gaps of 2.5 and 3.9 eV and, hence, afford no metallic property. [ABSTRACT FROM PUBLISHER]