Joint density of states at extended defects in CVD diamond, observed via highly spatially resolved electron energy loss spectroscopy

Results are presented of highly spatially resolved electron energy loss spectroscopy conducted on extended defects in CVD diamond. Analysis of the low energy loss regime shows that the joint density of states in the vicinity of dislocation nodes and secondary stacking faults, formed by incomplete dissociation of partial dislocations, can be different from that in perfect bulk material. Extra intensity in the joint density of states below the conduction band edge and in the lower conduction band was observed, with the most marked increase at around 6 eV. This is an indicator for sp ²-bond character. Spatially these states are too widely dispersed to be innate to the dislocation cores, and they are thought to arise from point defect segregation to extended defects. Kramers-Kronig and valence band plasmon analysis suggest an increase in the effective electron density and mass at the dislocation nodes.