We consider the prospects of locating and characterizing individual defect centers in bulk materials using electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM). We simulate STEM-EELS maps for two important defect centers in diamond, namely, the negatively charged nitrogen-vacancy defect and the neutral silicon-vacancy defect. We use density-functional theory to compute the defect electronic structure and a Møller potential formalism to compute the inelastic electron scattering. Our results indicate that it should be possible to use STEM-EELS to obtain the transverse locations of these defects to within about 1 nm. We calculate the plane-wave scattering cross sections for these individual defects to be of the order of 10-4 Å2, which indicates that the EELS signals should be within detectable limits. Calculated spectral maps and scattering cross sections are given as a function of the defect orientation, and we show that the results can be interpreted using a tight-binding description of the defect electronic structure.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics