First-principles calculations were made of the electron energy-loss spectra for bulk group-III nitrides and of spatially resolved electron energy-loss spectra for various edge and screw dislocations. The theoretical bulk low-loss electron energy-loss spectra, in the 0 to 10eV range, were in good agreement with recent experimental data. Gap states were found which were associated with undecorated full-core dislocations that led to absorption below the bulk onset energy in low-loss electron energy-loss spectroscopy. It was also found that the electrostatic potential at N atoms in the vicinity of an edge dislocation varied by an order of a volt, and probably precluded any simple interpretation of core-loss spectroscopy.

Influence of Dislocations on Electron Energy-Loss Spectra in Gallium Nitride. C.J.Fall, R.Jones, P.R.Briddon, A.T.Blumenau, T.Frauenheim, M.I.Heggie: Physical Review B, 2002, 65[24], 245304 (8pp)