Sub-monolayer physical layer deposition of Zn on Ag(111) substrate at room temperature is investigated using Auger electron spectroscopy, low energy electron diffraction and scanning tunneling microscopy. We identified an original Zn highly-anisotropic structure in the shape of finger-like inserted dendrite in front of Zn monolayer growth. On the basis of STM observations, a mechanism of inserted dendritic growth and a mechanism of its transition to layered growth are proposed.

Auger Electron Spectroscopy, Low Energy Electron Diffraction and Scanning Tunneling Microscopy have been used to study the atomic structure of a Zn monolayer deposited on Ag(111) and Ag(110) substrates at room temperature. On both faces, there is formation of a close packed monolayer of Zn covering the entire substrate surface and giving rise to specific Moire patterns. From a comprehensive LEED and STM data analysis, we deduce that the Zn monolayer adopts a (111) structure equivalent to a pure Zn layer rotated with respect to the silver substrate, of about 1.5 degrees on the Ag(111) face and of about 4.5 degrees on the Ag(110) face giving rise respectively to (root 156x root 156)R18 degrees and c(12 x 6) superstructures.

We report the preparation of single-crystal silicon nanoparticles with 15 to 22 nm diameter from calcium disilicide (CaSi2) by redox assisted chemical exfoliation using solution phase synthesis route. Silicon nanoparticles are found to be highly oriented with a predominant size of 18 nm. X-Ray diffraction, as well as transmission electron microscopy studies, confirm that the silicon nanoparticles are a diamond type and highly crystalline.

In this paper, using the same geometrical approach as for the (2  √  3  ×  2  √  3)R30° structure (Jamgotchian et al 2015 J. Phys.: Condens. Matter 27 395002), for the (√13  ×  √13)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 (√13  ×  √13)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.

The adsorption of silicon on Ag(110) forms long nano-ribbons, with very few atomic defects, perfectly aligned along the [ $$ \bar{1} $$ 10] direction of the Ag surface and all with the same width and same height. Despite many experimental and theoretical works, the atomic structure of the nano-ribbons is still debated and up until now, no proposed model agrees with all the experimental characterizations. The same controversy exists for thicker 3D nano-ribbons showing a pyramidal shape: are they stacks of silicene layers or nano-facetting of the substrate? Independently of the atomic structure it is well established that silicon nano-ribbons are hard to oxidize and can be used as templates to grow magnetic or organic nanostructures. In this chapter, we review the growth of silicon nano-ribbons on the Ag(110) surface.

The deposition of one silicon monolayer on Ag(1 1 1) 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 (2√3  ×  2√3)R30° structure, we propose a new atomic model of the silicene layer based on periodic arrangements of perfect areas of (2√3  ×  2√3)R30° surrounded by defect areas. A generalization of this model explains the main experimental observations: deviation of the average direction, Moiré 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.

The deposition of one monolayer of silicon on a Ag(lll) substrate induces the formation of silicene structures exhibiting different ordered phases, including a ()R30°, a (4×4) and a ()R13.9° superstructures. In tms paper we focus on the ()R30° phase. Using a combination of scanning tunneling microscopy and LEED observations, we show that this phase corresponds to a 11° rotation of the silicene sheet relative to the substrate orientation.

The deposition of one monolayer of silicon on a Ag(111) substrate induces the formation of silicene structures exhibiting different ordered phases, including a (2 root 3x2 root 3)R30 degrees, a (4 x 4) and a (root 13x root 13)R13.9 degrees superstructures. In this paper we focus on the (2 root 3x root 3)R30 degrees phase. Using a combination of scanning tunneling microscopy and LEED observations, we show that this phase corresponds to a 11 degrees rotation of the silicene sheet relative to the substrate orientation.

On Ag(111) substrate, the growth of a silicene layer (the equivalent of graphene for silicon) gives rise to four main superstructures due to the epitaxy between the silicene layer (honeycomb structure) and the Ag(111) substrate. Depending on both the substrate temperature and the deposition rate, the following superstructures were observed: (4×4), (× )R13.9°, (2× 2)R30° and (× )R19.1°. Each one corresponds to a specific rotation of the silicene layer with respect to the silver substrate. In this paper we show and discuss for each superstructure all the expected equivalent domains due to the symmetry properties of both the silicene honeycomb structure and the trigonal silver surface. Finally, we show, from STM images of the (2× 2)R30° superstructure, the role played by periodic local defects on the average direction of the superstructures.

We report results on the self-assembly of silicon nanoribbons on the (2x1) reconstructed Au(110) surface under ultra-high vacuum conditions. Upon adsorption of 0.2 monolayer (ML) of silicon the (2x1) reconstruction of Au(110) is replaced by an ordered surface alloy. Above this coverage a new superstructure is revealed by low electron energy diffraction (LEED) which becomes sharper at 0.3 Si ML. This superstructure corresponds to Si nanoribbons all oriented along the [-110] direction as revealed by LEED and scanning tunneling microscopy (STM). STM and high-resolution photoemission spectroscopy indicate that the nanoribbons are flat and predominantly 1.6 nm wide. In addition the silicon atoms show signatures of two chemical environments corresponding to the edge and center of the ribbons.

In this paper, we report the direct chemical synthesis of silicon sheets in gram-scale quantities by chemical exfoliation of pre-processed calcium disilicide (CaSi2). We have used a combination of x-ray photoelectron spectroscopy, transmission electron microscopy and energy-dispersive x-ray spectroscopy to characterize the obtained silicon sheets. We found that the clean and crystalline silicon sheets show a two-dimensional hexagonal graphitic structure.

Using scanning tunneling microscopy (STM), Auger electron spectroscopy, and low energy electron diffraction, we have observed a surprising complete dissolution at room temperature of one lead monolayer deposited by evaporation on an aluminum oxide thin film (∼0.8 nm thick) previously grown on Ag (111). We have observed the quasi-instantaneous diffusion of the lead deposit through the oxide layer to the silver/oxide interface. After the diffusion process, lead atoms form a Moiré superstructure, which is characterized by STM through the oxide layer. This unexpected behavior puts in light the very weak interaction between the aluminum oxide and the silver substrate.

Using low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), scanning tunneling microscopy (STM), and high-resolution photoelectron 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 degrees C and 400 degrees C, show at the beginning a rapid Si decrease followed by a slowing down up to a plateau equivalent to about one third of a silicon monolayer. STM images and LEED patterns, both recorded at room temperature just after annealing, reveal the formation of an ordered hexagonal superstructure of (root 3 x root 3)R30 degrees type. From these observations and from a quantitative analysis of HR-PES data, recorded before and after annealing, we propose that the (root 3 x root 3)R30 degrees superstructure corresponds to a two-dimensional Ni2Si surface silicide.

We report on experimental evidence for the formation of a two dimensional Si/Au(110) surface alloy. In this study, we have used a combination of scanning tunneling microscopy, low energy electron diffraction, Auger electron spectroscopy, and ab initio calculations based on density functional theory. A highly ordered and stable Si-Au surface alloy is observed subsequent to growth of a sub-monolayer of silicon on an Au(110) substrate kept above the eutectic temperature.

Silicene–the silicon-based counterpart of graphene–has a two dimensional structure that is responsible for the variety of potentially useful chemical and physical properties. The existence of silicene has been achieved recently owing to experiments involving epitaxial growth of silicon as stripes on Ag(001), ribbons on Ag(110), and sheets on Ag(111). The nano-ribbons observed on Ag(110) were found–by both high definition experimental scanning tunneling microscopy images and density functional theory calculations–to consist of an arched honeycomb structure. Angle resolved photo-emission experiments on these silicene nano-ribbons on Ag(110), along the direction of the ribbons, showed a band structure which is analogous to the Dirac cones of graphene. Unlike silicon surfaces, which are highly reactive to oxygen, the silicene nano-ribbons were found to be resistant to oxygen reactivity.

Low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and scanning tunnelling microscopy (STM) were used to study the reactive diffusion of one monolayer of silicon deposited at room temperature onto a Ni (111) substrate. We have done isochronal and isothermal kinetics by AES, and we observed in both cases a kinetics blockage on a plateau corresponding to around one third of a silicon monolayer. STM images and LEED patterns both recorded at room temperature just after annealing, reveal formation of an ordered hexagonal superstructure corresponding probably to a two-dimensional surface silicide.

The deposition of one silicon monolayer on the silver (111) substrate in the temperature range 150-300 °C gives rise to a mix of (4 × 4), (2√3 × 2√3)R30° and (√13 × √13)R13.9° superstructures which strongly depend 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 relative to the silver substrate. The morphologies of the STM images are explained from the position of the silicon atoms relative to the silver atoms. A complete analysis of all possible rotations of the silicene layer predicts also a (√7 × √7)R19.1° superstructure which has not been observed so far.