arXiv subjects

B. Aufray

Publications and source records attributed to B. Aufray.

5 recordsLinked to original sources

arXiv2016

A comprehensive analysis of the (R13xR13)R13.9° type II structure of silicene on Ag(111)

In this paper, using the same geometrical approach than for the (2R3x2R3) R30° structure (H. Jamgotchian et al., 2015, Journal of Physics. Condensed Matter 27 395002), for the (R13xR13)R13.9° type II structure, we propose an atomic model of the silicene layer based on a periodic relaxation of the strain epitaxy. This relaxation creates periodic arrangements of perfect areas of (R13xR13)R13.9° type II structure surrounded by defect areas. A detailed analysis of the main published experimental results, obtained by Scanning Tunneling Microscopy and by Low Energy Electron Diffraction, shows a good agreement with the geometrical model.

cond-mat.mtrl-sci↗

arXiv2015

A comprehensive study of the (2R3x2R3)R30 structure of silicene on Ag(111)

The deposition of one silicon monolayer on Ag(111) gives rise to a set of superstructures depending on growth conditions. These superstructures are correlated to the epitaxy between the honeycomb structure of silicon (so called silicene) and the silver substrate. In this paper, from a detailed re-analysis of experimental results, obtained by Scanning Tunneling Microscopy and by Low Energy Electron Diffraction on the (2R3x2R3)R30 structure, we propose a new atomic model of the silicene layer based on periodic arrangements of perfect areas of (2R3x2R3)R30 surrounded by defect areas. A generalization of this model explains the main experimental observations: deviation of the average direction, Moire patterns and apparent global disorder. In the frame of the proposed model, the apparent disorders observed on the STM images, would be topological effects, i.e. the silicene would keep a quasi-perfect honeycomb structure.

cond-mat.mtrl-sci↗

arXiv2013

Formation and stability of a two-dimensional nickel silicide on Ni (111) an Auger, LEED, STM, and high-resolution photoemission Study

Using low energy electron diffraction (LEED), Auger electron spectroscopy (AES), scanning tunnelling microscopy (STM) and high resolution photo-electron spectroscopy (HR-PES) techniques we have studied the annealing effect of one silicon monolayer deposited at room temperature onto a Ni (111) substrate. The variations of the Si surface concentration, recorded by AES at 300°C and 400°C, show at the beginning a rapid Si decreasing followed by a slowing down up to a plateau equivalent to about 1/3 silicon monolayer. STM images and LEED patterns, both recorded at room temperature just after annealing, reveal the formation of an ordered hexagonal superstructure(rot3xrot3)R30°-type. From these observations and from a quantitative analysis of HR-PES data, recorded before and after annealing, we propose that the (rot3 x rot3)R30°superstructure corresponds to a two dimensional (2D) Ni2Si surface silicide.

cond-mat.mtrl-sci↗

arXiv2012

Growth of silicene layers on Ag(111): unexpected effect of the substrate temperature

The deposition of one silicon monolayer on the silver (111) substrate in the temperature range 150-300$^\circ$C, gives rise to a mix of (4$\times$4), ($2\sqrt{3}\times 2\sqrt{3}$)R30$^\circ$ and ($\sqrt{13}\times\sqrt{13}$)R13.9$^\circ$ superstructures which strongly depends on the substrate temperature. We deduced from a detailed analysis of the LEED patterns and the STM images that all these superstructures are given by a quasi identical silicon single layer with a honeycomb structure (i.e. a silicene-like layer) with different rotations relatively to the silver substrate. The STM images morphology are explained from the relative position of the silicon atoms relative to the silver atoms. A complete analysis of all possible rotations of the silicene layer predicts also a ($\sqrt{7}\times\sqrt{7}$)R19.1$^\circ$ superstructure which has not been observed so far.

cond-mat.mtrl-sci↗

arXiv2008

Physics of Silicene Stripes

Silicene, a monolayer of silicon atoms tightly 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 material in condensed matter physics. If existing, it would also reveal a cornucopia of new physics and potential applications. Here, we reveal the epitaxial growth of silicene stripes self-aligned in a massively parallel array on the anisotropic silver (110) surface. This crucial step in the silicene gold rush could give a new kick to silicon on the electronics road-map and opens the most promising route towards wide-ranging applications. A hint of superconductivity in these silicene stripes poses intriguing questions related to the delicate interplay between paired correlated fermions, massless Dirac fermions and bosonic quasi-particules in low dimensions.

cond-mat.mtrl-sci↗