Structural and electronic properties of<i>h</i>-BN

Effects of stacking behavior of hexagonal basal layers to the structural stability and electronic properties of h-BN were investigated thoroughly using first-principles calculations based on the density-functional theory local-density approximation. Three of five possible h-BN structures with ``good'' stacking were found to be stable or substable. Considering that intrinsic stacking fault exist in real h-BN crystals which results in mixed stacking behavior, the experimentally observed large interlayer spacing of structures with stacking disorder such as PBN and t-BN can be understood. A substable structure with a direct band gap of about 3.395 eV was predicted. The existence of this substable structure and related intrinsic stacking fault in real h-BN explains the discrepancy in the nature of the band gap and the large variation in the observed band-gap values of h-BN.