[Zurück]

S. Lazar, C. Hébert, H.W. Zandbergen:
"Investigation of hexagonal and cubic GaN by high-resolution electron energy-loss spectroscopy and density functional theory";
Ultramicroscopy, 98 (2004), S. 249 - 257.

Investigation of hexagonal and cubic GaN by high-resolution electron energy-loss spectroscopy and density functional theory

Dedicated to Professor Fang-hua Li on the occasion of her 70th birthday

S. Lazar Corresponding Author Contact Information, E-mail The Corresponding Author, a, C. Hébert b and H. W. Zandbergen a

a National Centre for HREM, Department of Nanoscience, Delft University of Technology, Rotterdamseweg 137, Delft 2628 AL, The Netherlands
b Institut. für Festkörperphysik TU Wien, Wiedner Hauptstrasmall beta, Greeke 8-10, Wien A-1040, Austria

Received 21 May 2003; Revised 25 June 2003. Available online 18 September 2003.


Abstract

High-resolution electron energy-loss spectroscopy in a transmission electron microscope is a very powerful method for the study of electronic structure of materials. The fine structure of Ga L2,3 and N ionization edges in c-GaN and h-GaN was studied using a TEM equipped with a monochromator and high-resolution energy spectrometer. The experimental results were compared with the results of calculation based on the density functional theory using the Wien2k code and show that the best fit is achieved when the core hole effect is taken into account. The effect of the core hole value and the supercell size on the energy-loss near-edge structure have been investigated. A different behaviour was found for c-GaN and h-GaN: better agreement is obtained for a 0.5 core hole for h-GaN and for a full core hole for c-GaN. The anisotropic behaviour of the experimental spectra and calculated spectra for h-GaN have been studied and the "magic" angle was determined.

Author Keywords: Author Keywords: High-resolution electron energy-loss spectroscopy; Near-edge structure; Density functional theory; GaN

http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC04970283

doi:10.1016/j.ultramic.2003.08.018