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

TL;DR

This study investigates the formation and stability of a two-dimensional nickel silicide on Ni (111) using multiple surface analysis techniques, revealing the structure and composition of the resulting surface alloy.

Contribution

It provides a detailed characterization of a 2D Ni2Si surface silicide on Ni (111), combining LEED, AES, STM, and HR-PES data to elucidate its structure and formation process.

Findings

Formation of an ordered (rot3xrot3)R30° superstructure.

Identification of a 2D Ni2Si surface silicide.

Surface silicon concentration stabilizes at about 1/3 monolayer.

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{\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.