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{\deg}C and 400{\deg}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{\deg}-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{\deg}superstructure corresponds to a two dimensional (2D) Ni2Si surface silicide.Comment: Journal Physical Review B (2012

Evolution of early formed NiSi2 during the reaction between Ni(W, Pt) films and Si (001)

The early formation of NiSi2 has been observed during the solid state reaction between Ni(W,Pt) films and Si (001) substrates at a temperature of 295 °C. The maximum contents of W and Pt additions are ~28 at.%. In-situ X-ray diffraction (XRD) measurements and rapid thermal processing (RTP) were performed at different temperatures and the annealed samples were subsequently characterized by atom probe tomography (APT). Distinct structures containing different silicides were observed and it enables us to put forward a mechanism showing the evolution of early formed NiSi2. Ni diffusion slows down resulting from the effect of alloying elements and the redistribution of Pt and W strongly influences the formation sequence of Ni silicides. Keywords: NiSi2, Ni silicides, Alloying elements, Phase sequence, W and P

Significado da internação no centro de terapia intensiva para o familiar do paciente idoso

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Hipotermia no pós-operatório imediato

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Correction of secondary ion mass spectrometry profiles for atom diffusion measurements

International audienceA simple method is proposed in order to correct experimental secondary ion mass spectrometry (SIMS) profiles. This method uses only one parameter which is experimentally accessible. It is tested in the case of As SIMS profiles in Si(001) acquired with three different primary ion beam energies: 1, 3, and 9 keV. This method is shown to give consistent corrections. The correction of SIMS profiles measured in a same sample with different analysis conditions leads to the same As distribution

Ordered silicon structures on silver (100) at 230°C

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Ordered silicon structures on silver (100) at 230°C

The growth of silicon at 230$^{\circ}$C on the silver (100) surface has been studied by Auger Electron Spectroscopy (AES), Low Energy Electron Diffraction (LEED) and Photo Electron Spectroscopy (PES). At this temperature, the growth starts with the formation of one complete monolayer showing a p($3\times 3$) superstructure. Beyond, the p($3\times 3$) evolves towards a “complex” superstructure (which has not been indexed) corresponding to the formation of silicon islands. Surprisingly, the PES results reveal that Si presents a strong metallic character at least up to 1.7 ML

AES measurements of Sb mass transport in amorphous Si thin films

Sb diffusion in an amorphous Si thin film and Sb segregation kinetics onto the Si film were studied by Auger electron spectroscopy in the temperature range of 600-723 K. Segregation factors and antimony diffusivities were estimated from the experimental kinetics curves, on the basis of the Lea and Seah model, the Sb bulk concentration in Si films being studied by TEM. Sb diffusivities in amorphous Si proved to be 10-12 orders of magnitude higher than that of measured in crystalline Si, the pre-exponential factors being of the same order of magnitude

Técnicas de computação no ensino de física : pêndulo simples e movimento de projéteis

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