Přednášející: Dr. Guy Le Lay (CINaM-CNRS, Campus de Luminy, Marseille, France)
Místo: Institute of Physics ASCR, Cukrovarnická 10, Library, building A
Jazyk: anglicky
Silicene [1], the alternative of graphene for silicon, has been theoretically conjectured recently. Its synthesis has just been reported: silicon deposition onto Ag(110) surfaces reveals the formation of silicon nano-ribbons (NRs), in a massively parallel arrangement along the [-110] direction. Their atomic geometry was derived by high-resolution STM images showing a honeycomb arrangement, i.e., a silicene-like structure, further supported by theoretical calculations. These one-dimensional (1D) silicene NR's, showing quantized/edge states in STS imaging, self-assemble by lateral compaction to form a grating with a pitch of ~ 2 nm covering the entire substrate surface. The band dispersion along the NRs direction reveals, as for graphene, massless Dirac fermions resulting from the 1D projection of ∏ and * Dirac cones.This points to sp2 hybridization, which is further confirmed
1) by the incidence angle dependence of Electron Energy Loss Spectra near the silicon K absorption edge: the measured anisotropy is very similar to that found for the carbon K edge of HOPG graphite,
2) by the strong resistance toward oxidation. Recently, two-dimensional silicene-like sheets have been also obtained in Marseille upon Si deposition onto Ag(111). Finally, the implications of these novel results for new physics and applications will be discussed.
[1] G.. G.. Guzman-Verri and L. C. Lew Yan Voon, Phys. Rev. B 76 (2007) 75131
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