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

Abstract

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 ( 3 3) 30 R ×°-type. From these observations and from a quantitative analysis of HR-PES data, recorded before and after annealing, we propose that the ( 3 3) 30 R ×°superstructure corresponds to a two dimensional (2D) Ni 2 Si surface silicide.

Structure determination of the ordered 3×3R30° phase of Ni2Si and Ni2Ge surface alloys on Ni(111) via low-energy electron diffraction

“…It should be noted that a higher temperature (650-850 K) was required for Si substitution of Ni atoms to form the surface alloy in the Si on Ni(111) system compared to that for the Si on Ag(111) system, which is consistent with the fact that Ni\ \Ni bond dissociation energy is higher than that for Ag\ \Ag [31]. For Si adsorption on Ni(111), electron transfer between the Si and Ni atoms has been reported at high temperatures [23], which indicates that the Si atoms strongly interact with the Ni atoms. Lalmi [23].…”

“…ÞR30 phase [23], but did not do a detailed structural analysis. To the best of our knowledge, there are no available reports concerning Ge on Ni(111).…”

“…Bulk phase diagrams suggest that there is the possibility for Si or Ge to diffuse into bulk Ni, which is not the case for the reverse system [25]. Lalmi et al investigated a Si/Ni system to determine the effect of the nonequivalence of Ni/Si and Si/Ni deposition sequences on the initial stages of Schottky barrier formation [23]. They reported the formation of a 2-D nickel silicide with one-third monolayer (ML) Si-coverage as a ð ffiffiffi…”

“…Typical examples of S/M systems include Si/Ag, Ge/Ag, and Si/Ni [21][22][23][24]. Recently the S/M systems have drawn attention in nanophysics to understand the surface structure and reaction kinetics at the interface.…”

First-Principles Study of Silicon-Embedded Ni(110)

“…The interfaces are usually formed by depositing Ni onto Si substrates, followed by a thermal treatment that leads to epitaxial Si-rich silicide overlayers. Ni-silicides may also be formed by Si deposition onto Ni substrates, and in this case Ni-rich silicides might be formed [4][5][6][7].…”