Detection of inactive defects in crystalline silicon by high-resolution transmission-electron energy-loss spectroscopy

We have applied high-resolution transmission electron energy-loss spectroscopy to explore the electronic structure of a reconstructed defect in the interior of Si crystal. Despite the electronic and optical inactivity of the defects, the $L_{2,3}$ near-edge structure becomes sharp within the narrow energy range (less than 1 eV) whenever an electron probe locates on the defects. Our analysis based on ab initio computations has suggested that the sharpened near edge arises from the odd-membered atomic ring in the defects.