Figure 1: Schematic of the boron nitride crystal structures. The hexagonal (hBN), cubic(cBN), rhombohedral(rBN), and wurtzite(wBN) phases of boron nitride are shown with dark balls representing boron atoms and white balls representing nitrogen. Note that the hexagonal crystal structure has A-B-A stacking, while the rBN has A-B-C-A stacking of the hexagonal-like sheets. The wurtzite crystal structure can be viewed as a distortion of the cubic phase where the tetrahedral bonds in one direction are expanded to form a layered compound.
Figure 2: Boron 1s core-level photoabsorption for hBN, cBN, rBN, and wBN phases of boron nitride and a BN thin film grown by ion-assisted, pulsed laser deposition. Each spectrum was photon flux normalized and scaled. Note that the pi* feature at 192.0 eV that is identified with hBN is also present in the rBN and BN/Si samples.
Figure 3: Nitrogen 1s photoabsorption for the hBN, cBN, rBN,
wBN, and BN/Si samples presented in Figure 1. Here the
resonances are not as prominant as those at the B 1s edge,
however, the relative energy positions and intensities are
valuable for understanding the atomic distribution for the
electronic density of states when compared to the
corresponding B 1s features.