Electronic properties of Sn/Si(100) ordered interfaces

We studied the optical and electronic structures of the different ordered superstructures of Sn grown on Si(100)2 x 1 by means of angular resolved photoemission (ARUPS), surface differential reflectivity (SDR), Auger and low energy electron diffraction (LEED). Five different reconstructions, showing a semiconductor character, have been found. For the (5 x 1)Sn/Si(100) interface one dispersive surface state is identified, 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 the 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.