ELECTRONIC-PROPERTIES OF SN SI(100) ORDERED INTERFACES/

We studied the optical and electronic structures of the different orde red superstructures of Sn grown on Si(100)2 x 1 by means of angular re solved photoemission (ARUPS), surface differential reflectivity (SDR), Auger and low energy electron diffraction (LEED). Five different reco nstructions, showing a semiconductor character, have been found. For t he (5 x 1)Sn/Si(100) interface one dispersive surface state is identif ied, while for the other superstructures, c(4 x 4), (6 x 2) and (4 x 1 ), the ARUPS spectra show two non-dispersive tin-induced states. For t he c(8 x 4) reconstruction three surface states are clearly identified : one non-dispersive state at 0.9 eV below the Fermi level, one state at the border of the surface Brillouin zone with a binding energy of 1 .7 eV and one highly dispersive state between 1.6 and 2.8 eV below the Fermi level. On this surface SDR revealed four optical transitions in the energy range between 1.3 and 3.5 eV. (C) 1997 Elsevier Science B. V.