N-K ELNES study of anisotropy effects in hexagonal AlN.

Anisotropic effects in hexagonal aluminium nitride have been studied by electron energy-loss spectroscopy (EELS) in the N-K energy loss near edge structure (ELNES). Experimental data acquired with different collection angles and with a nearly parallel incident electron beam aligned along the c-axis have been compared to simulations based on ab initio calculations. The extraction of intrinsic parallel I|| (with momentum transfer q || c axis) and perpendicular I perpendicular (with momentum transfer q perpendicular c axis) components has been performed directly from the experimental spectra. This has been done according to their description as linear combinations of I|| and I perpendicular, with adequate weights deduced from a geometrical model of anisotropic behaviour.