book of abstracts - IM2NP

A B S T R A C T S MONDAY, JUNE 28 N A N O S E A 2 0 1 0
11h30-11h50
Many body approach for the excitonic effects in 1D and 2D silicon doped
nanostructures.
Del Sole ((1) Laboratoire des Solides Irradies, Ecole Polytechnique - CNRS
(2) Dip. di Fisica, CNISM, Universita‟ di Roma Tor Vergata, Roma, Italy
(3) Dip. di Scienze e Metodi dell'Ingegneria, Università di Modena e Reggio Emilia, Italy
(4) European Theoretical Spectroscopy Facility)
Silicon Nanowires (Sinw) and Silicon Nanoribbons (Sinr) are one- (1D) and two- (2D) dimensional
nanostructures which are attracting in the last years increasing interest for potential nanoelectronic and
nanophotonic applications. Sinw have made an impact in applications in fields as diverse as electronics,
photonic, sensing, biology and photovoltaics , while Sinr, recently realized, seems to be promising as well,
maybe even more than the 1D systems for silicon basednanotechnology application.
In this theoretical work we investigate mainly the electronic and the optical properties of 1D and 2D system
with and without the presence of impurities. The size and doping dependence of the electron-hole exchange
interaction in Si nanowires is investigated from first-principles. In pure Si nanowires we found excitonic
exchange splittings in very good agreement with the experimental results for porous silicon. For n-doped Si
nanowires a giant singlet-triplet splitting, three order of magnitude bigger than in bulk silicon, is predicted as
due to the dramatic enhancement of the electron and the hole probability of being in the same place at the
same time. For the Sinr we have calculated the dielectric function for different light polarization in and
outside the plane by taking into account many body effect.
11h50-12h20
One-dimensional Mn nano-wires on a ordered array of silicon nanoribbons.
P. De Padova1, M. E. Dávila2, F. Hennies3, A. Pietzsch3, N. Shariati3, C.
Ottaviani1, C. Quaresima1, B. Olivieri4, F. Ronci1, S. Colonna1, A. Cricenti1, B.
Aufray5, G. Le Lay5 (1CNR-ISM, via Fosso del Cavaliere, 00133 Roma, Italy. 2Instituto de Ciencia de
Materiales de Madrid, CSIC, Cantoblanco 28049 Madrid, Spain. 3MAX-Lab, Lund University, Box 118 221 00
Lund, Sweden. 4Consiglio Nazionale delle Ricerche-ISAC, via Fosso del Cavaliere, 00133 Roma, Italy. 5CINaM-
CNRS, Campus de Luminy, Case 913, 13288 Marseille Cedex 9, France)
Silicon nano-ribbons (SiNRs) are one of the more promising systems for studying the role of dimensionality
on physical properties for potential applications in nanoscale electronics or spintronics. Room temperature
(RT) deposition of low coverages of Si on the Ag(110) surface produces massively parallel Si nano-ribbons
(SiNRs) along the [–110] direction. They have a magic width of 16 Å, unprecedented spectral signatures in
valence band and core-level spectroscopy and unique burning match-like oxidation behavior. Upon
annealing, a very well ordered array of SiNRs, in a 5x2/5x4 arrangement, is obtained on the Ag(110)
substrate.
Si was evaporated on Ag(110) substrate at a rate of ~ 0.03 ML/min from a Si source, while the sample was
heated at 440 K to obtain a dense array SiNRs (5x2/5x4 reconstruction). LEED observations were used to
monitor the x2 and 5x2/5x4 superstructures.
Core level spectroscopy data have been taken at the VUV beamline of ELETTRA (Trieste). The photon
energies used for Si 2p core level was 135.8 eV.
Here we report the electronic and structural properties of Mn grown on a dense array of well-ordered SiNRs
on Ag(110). High-resolution Si 2p core levels show an interesting selective adsorption of Mn atoms on the
SiNRs as clearly evidenced by the collection of high-resolution scanning tunneling microscopy images. We
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