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  • Küçük Resim
    Öğe
    Atomic and electronic structures of T1/Si(111)-(root 3x root 3)
    (Elsevier Science Bv, 2008) Özkaya, Sibel; Cakmak, Mükerrem; Alkan, Berk
    Ab initio calculations, based on pseudopotentials and density functional theory, have been performed to investigate the atomic and electronic structure of the T1/Si(1)-(root 3x root 3) surface. In the (root 3x root 3) reconstruction of surface, the two possible adatom geometries were considered: adsorption in Mold symmetric hollow sites (H-3 model) and in 4-fold atop sites (T-4 model). We have found that the energy difference between these two models is indeed very small within the energy of 0.03 eV. By calculating the electronic band structure for the T4 configuration, we have also identified two occupied and one unoccupied surface state. We have also determined the origin of these surface states. Our results are seen to be in agreement with the recent angle-resolved photoelectron spectroscopy. (c) 2008 Elsevier B.V. All rights reserved.
  • Küçük Resim
    Öğe
    Atomic and electronic structures of the group-IV elements on Si(111)-(root 3x root 3) surface
    (Publishing Ltd, 2008) Özkaya, Sibel; Çakmak, Mükerrem; Alkan, Berk; Johansson, LSO; Andersen, JN; Gothelid, M; Helmersson, U; Montelius, L; Rubel, M; Setina, J; Wernersson, LE
    We have examined the Si(111) surface with 1/3 monolayer of group-IV elements within the abinitio density functional theory We have considered two possible threefold-c oordinated sites for the atom adsorption: (i) H-3 site (this site is directly above a fourth-layer Si atom and (ii) T-4 site (directly above a second-layer Si atom). For the atoms Ge, Sn, and Pb, the T-4 position always gives the most stable configuration, comparing with the H-3 site. The calculated energy difference between T-4 and H-3 for Pb, Ge, and Sn, is 0.32 eV, 0.59 eV, and 0.41eV, respectively. We have also presented electronic band structure and orbital character of the surface states of the Sn/Si(111)-(root 3x root 3)surface.