SMALL BAND-GAP GRAPHITIC CBN LAYERS

Electronic band structure computations for a perfect hexagonal layer o f CBN have been performed via density functional theory using the loca l density approximation to the exchange-correlation potential. A small band gap of similar to 0.2 eV is thereby obtained, with the band gap being offset away from the central: Gamma-point of the two-dimensional Brillouin zone. These results are rationalized in terms of a simple e mpirical Huckel model, for which simple structural criteria for a zero band gap are noted. Special attention is paid to the case with a mini mum content of carbon, and some comparison is made to earlier band str uctures for two different geometrical layers of C2BN. (C) 1998 Elsevie r Science Ltd. All rights reserved.