Calculated and experimental low-loss electron energy loss spectra of dislocationsin diamond and GaN

Abstract

First-principles calculations of electron energy loss (EEL) spectra for bulk GaNand diamond are compared with experimental spectra acquired with a scanningtunnelling electron microscope offering ultra-high-energy resolution in low-lossenergy spectroscopy. The theoretical bulk low-loss EEL spectra, in theEg to10 eV range, are in good agreement with experimental data. Spatially resolvedspectra from dislocated regions in both materials are distinct from bulk spectra.The main effects are, however, confined to energy losses lying above the bandedge. The calculated spectra for low-energy dislocations in diamond are consistentwith the experimental observations, but difficulties remain in understanding thespectra of threading dislocations in GaN.