Electron energy loss near edge structure (ELNES) spectra of AlN and AlGaN: A theoretical study using the Wien2k and Telnes programs

Several aspects of the modelling of the energy loss near edge structure (ELNES) using the Wien2k code and the Telnes program are discussed in this paper. A case study with ground state, partial and full core-hole calculations of wurtzite AlN was performed and the results were compared with experimental transmission electron microscopy data. The best agreement with the experimental observations was obtained for the full core-hole case. Changes in the ELNES spectra for various core-hole charges are explained by investigating the site and symmetry projected density of states. Directionally resolved N K-edge ELNES of AlN are discussed and the magic angle beta approximate to 2.5 mrad is identified which is in a good agreement with other theoretical predictions. Finally, preliminary results on a compositional study of AlxGa1-xN are explored. (C) 2007 Elsevier Ltd. All rights reserved.