SURFACE-STATES ON SI(111) 7X7 STUDIED BY LOW-ENERGY ELECTRON LOSS SPECTROSCOPY

The clean Si(lll) 7 × 7 surface is studied by low‐energy electron diffraction (LEED), Auger electron spectroscopy (AES), and low‐energy electron loss spectroscopy (ELS). For primary energies up to 100 eV the ELS spectra show more characteristic loss peaks than the spectra published until now. The spectra are interpreted using the dielectric model, the density‐of‐states model, and the interband excitation model applied to the surface energy band structure calculated by Pandey and Phillips. As a result the majority of the characteristic energy losses are due to electron interband transitions from filled surface states into empty surface or volume states. In contrast to that, most of the observed loss peaks for higher primary energies, as demonstrated for 400 eV, can be interpreted as interband transitions from volume to volume states. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA