Silicon on Ir(111)

Fast X-ray photoelectron spectroscopy measurements and density functional theory calculations were used to establish whether at low coverage, Si adatoms float on the Ir surface or displace substrate atoms and are incorporated into the metal. The results show that the interface is unstable with respect to the formation of Si–Ir alloys, a behavior that excludes the formation of a silicene layer on the Ir(111) substrate.

M. Satta et al., Nanoscale 10, 7085 (2018).

The adsorption of Si atoms on a metal surface might proceed through complex surface processes, whose rate is determined differently by factors such as temperature, Si coverage, and metal cohesive energy. Among other transition metals, iridium is a special case since the Ir(111) surface was reported first, in addition to Ag(111), as being suitable for the epitaxy of silicene monolayers.
In this study we followed the adsorption of Si on the Ir(111) surface via high resolution core level photoelectron spectroscopy, starting from the clean metal surface up to a coverage exceeding one monolayer, in a temperature range between 300 and 670 K. Density functional theory calculations were carried out in order to evaluate the stability of the different Si adsorption configurations as a function of the coverage.
Results indicate that, at low coverage, the Si adatoms tend to occupy the hollow Ir sites, although a small fraction of them penetrates the first Ir layer. Si penetration of the Ir surface can take place if the

energy gained upon Si adsorption is used to displace the Ir surface atoms, rather then being dissipated differently.
At a Si coverage of ∼1 monolayer, the Ir 4f spectrum indicates that not only the metal surface but also the layers underneath are perturbed. Our results point out that the Si/Ir(111) interface is unstable towards Si–Ir intermixing, in agreement with the silicide phase formation reported in the literature for the reverted interface.

Retrieve article
The adsorption of silicon on an iridium surface ruling out silicene growth;
M. Satta, P. Lacovig, N. Apostol, M. Dalmiglio, F. Orlando, L. Bignardi, H. Bana, E. Travaglia, A. Baraldi, S. Lizzit, and R. Larciprete;
Nanoscale 10, 7085-7094 (2018).
Last Updated on Friday, 22 January 2021 16:17