Electronic structure of aluminum nitride: Theory and experiment

We report the results of a vacuum ultraviolet (VUV) study of single crystal and polycrystalline AlN over the range 4–40 eV and compare these with theoretical optical properties calculated from first principles using an orthogonalized linear combination of atomic orbitals in the local density approximation. The electronic structure of AlN has a two-dimensional (2D) character indicated by logarithmic divergences at 8.7 and 14 eV. These mark the centers of two sets of 2D critical points which are associated with N 2p→Al 3s transitions and Al=N→Al 3p transitions, respectively. A third feature is centered at 33 eV and associated with N 2s→Al 3d transitions.