Electronic structure of localized Si dangling-bond defects by tunneling spectroscopy

Scanning tunneling microscopy is used to determine the atomic structure, charge state, and electronic energy spectrum of isolated Si dangling-bond defects at the Al/Si(111) surface. Si adatoms substituting for Al in the first atomic layer give rise to a dangling-bond defect state near -0.4 eV which is strongly localized in space. Tunneling spectra and local band-bending measurements are inconsistent with simple one-electron band theory and demonstrate the importance of many-electron effects. © 1988 The American Physical Society.