Electron energy loss spectroscopy of thin films of GaN and diamond was carried out, using nm spatial resolution, in a dedicated scanning transmission electron microscope. It was possible to extract the scattering intensity down to energy losses of 2eV with an energy resolution of 0.36eV. This was achieved by using a high spectrometer dispersion. A specific attempt was made to determine changes in the electronic band structure, reflected in the inelastic low loss scattering distribution at dislocations. First-principles calculations, within the local density approximation to density functional theory, of the band structure used to simulate low electron energy loss spectra revealed band-gap states that were associated with all dislocation types in GaN as well as in diamond. Core loss calculations for GaN predicted potential shifts at edge dislocations, due to the piezo-electric effect. The theoretical findings were in very good agreement with measurements.

Energy Loss Spectroscopy of Dislocations in GaN and Diamond - a Comparison of Experiment and Calculations. A.Gutiérrez-Sosa, U.Bangert, A.J.Harvey, C.Fall, R.Jones: Diamond and Related Materials, 2003, 12[3-7], 1108-12