EELS spectra of In/Si(111) surface phases

Formation of surface phases in the In/Si(111) system has been studied using EELS; AES and LEED techniques. The EELS spectra of root3 x root3, 4 x 1 and root3 x root7-In surface phases available in literature were reviewed and analyzed with respect to their compositions. The energy loss peak near 12.6 divided by 13.5 eV is shown to be characteristic of these surface phases and cannot be related to the losses of clean Si or In. The EELS spectra of delta - 7 x 7-In surface phase have been obtained, as well as the spectra of root3 x root7-In disordered surface phases formed after destruction of the 7 x 7 order. The formation of these surface phases is straightforwardly reflected in EELS, that is considered from the viewpoint of electrons redistribution between In and Si atoms and bulk Si substrate. In a similar way we explained the observed energy loss peaks in the spectra of root3 x root3, 4 x 1 and root3 X root7-In surface phases and estimated the Si in-phase concentration in the last case.