C. Leandri

Graphene-like silicon nanoribbons on Ag(110) : a possible formation of silicene

Scanning tunneling microscopy (STM) and ab initio calculations based on density functional theory (DFT) were used to study the self-aligned silicon nanoribbons on Ag(110) with honeycomb, graphene-like structure. The silicon honeycombs structure on top of the silver substrate is clearly observed by STM, while the DFT calculations confirm that the Si atoms adopt spontaneously this new silicon structure.

Formation of a one-dimensional grating at the molecular scale by self-assembly of straight silicon nanowires

Upon submonolayer deposition of silicon onto the anisotropic silver (110) surface flat lying individual Si nanowires, all oriented along the [−110] direction, can be grown at room temperature with a high aspect ratio. Upon deposition at ∼200°C, these one-dimensional nanostructures self-assemble by lateral compaction to form a regular array of essentially identical nanowires, ∼1.6nm in width, covering uniformly the entire substrate surface. They realize, at macroscopic sizes, a highly perfect one-dimensional grating with a molecular-scale pitch of just 2nm.Upon submonolayer deposition of silicon onto the anisotropic silver (110) surface flat lying individual Si nanowires, all oriented along the [−110] direction, can be grown at room temperature with a high aspect ratio. Upon deposition at ∼200°C, these one-dimensional nanostructures self-assemble by lateral compaction to form a regular array of essentially identical nanowires, ∼1.6nm in width, covering uniformly the entire substrate surface. They realize, at macroscopic sizes, a highly perfect one-dimensional grating with a molecular-scale pitch of just 2nm.

Burning match oxidation process of silicon nanowires screened at the atomic scale

Silicon oxide nanowires hold great promise for functional nanoscale electronics. Here, we investigate the oxidation of straight, massively parallel, metallic Si nanowires. We show that the oxidation process starts at the Si NW terminations and develops like a burning match. While the spectroscopic signatures on the virgin, metallic part, are unaltered we identify four new oxidation states on the oxidized part, which show a gap opening, thus revealing the formation of a transverse internal nanojunction.

Growth and dissolution kinetics of Au/Pb(1 1 1): an AES-LEED study

The growth of Au on a Pb(1 1 1) surface is studied by AES-LEED at room temperature (RT). After deposition of 1/3 Au monolayer (ML), LEED observations reveal a p( p 3 � p 3)R308 superstructure. Beyond this coverage, no superstructure is observed. From Au and Pb Auger peak intensities, we deduce that the growth corresponds to the formation of an inter-metallic compound AuxPby continuously growing under a floating Pb ML. The dissolution kinetics of one Au ML recorded at various temperatures systematically show a plateau (a slowing down) at a surface concentration corresponding to 1/3 ML. From a quantitative evaluation of the AES data we propose that the p( p 3 � p 3)R308 superstructure corresponds to a surface alloy with composition AuPb2 buried under 1 Pb ML. Such a surface alloy has been previously measured after annealing of a Au(Pb) 0.45 at.% solid solution [Surf. Rev. Lett. 4 (1997) 1139], we propose that the slowing down observed during the dissolution kinetics is also the signature of this unexpected segregation behaviour of Au. It could be related to the fact that the surface energy of this inter-metallic compound (AuPb2) is lower than the surface energy of both constitutive elements (Au and Pb). # 2003 Elsevier Science B.V. All rights reserved. PACS: 68.47.De; 68.08.De; 68.55.-a

Graphene-like Silicon Nano-ribbons on the Silver (110) Surface

Silicene, a monolayer of silicon atoms packed into a two-dimensional honeycomb lattice is the challenging hypothetical reflection in the silicon realm of graphene, a one-atom thick graphite sheet, presently the hottest new material in condensed matter physics and nanotechnology. If existing, it would also reveal a cornucopia of new physics and potential applications. Here, we reveal the catalytic growth of graphene-like silicon nano-ribbons self-aligned in a massively parallel array on the anisotropic Ag(110) surface. We compare with one-dimensional (1D) structures formed, more classically, the other way around, upon depositing gold or silver on the silicon (111) surface. Finally, we envisage wide ranging applications for these novel silicene stripes.