Electronic structure of a and g phases of Si 111/–(3 =(3 –Sn

This work presents a detailed comparison of the electronic properties of two phases a and g.of the prototypical Si 111.–ʹ3 =ʹ3 –Sn system, focussing on the empty surface states. The latter reconstruction has been studied at room temperature with inverse photoemission KRIPES.. For the g-phase characterised by an equal amount of Sn and Si adatoms, a charge transfer towards the Sn adatom leaves an empty surface state localised on Si adatoms, and observed in KRIPES 0.4 eV above the Fermi level EF.at the surface Brillouin zone SBZ.center. The band gap of this semiconducting g-phase is estimated around 0.5 eV. In contrast, the a phase with only Sn adatoms shows a metallic behaviour and two distinct adatom-derived empty surface states. q2000 Elsevier Science B.V. All rights reserved.