Modelling electron energy-loss spectra of dislocations in silicon and diamond

Electron energy-loss spectroscopy (EELS) performed near dislocation cores is one of the few experimental techniques that can yield valuable information about the electronic levels associated with dislocations. In this study, using ab initio calculations, we model and predict low-loss and core-excitation EELS spectra acquired on various dislocation cores in silicon and diamond, and compare the results with bulk spectra. In diamond, we consider in particular 90degrees partial glide, undissociated 60degrees shuffle, and 30degrees partial dislocations. We find evidence of empty states localized on diamond shuffle dislocation cores and positioned below the bulk band edge, which modify the EELS spectrum. In silicon, we find changes-analogous to those seen experimentally-in core-excitation EELS near stacking faults and partial glide dislocations. (C) 2001 Elsevier Science B.V. All rights reserved,