Issue 5, 2018

The mechanism for the stabilization and surfactant properties of epitaxial silicene

Abstract

Using real-time in situ scanning tunneling microscopy and density functional theory simulations, we have studied the growth of Si films on Ag(111) beyond the silicene monolayer, evidencing the existence of metastable phases and an original growth mechanism. Above monolayer Si coverage, an initial Image ID:c7nr06833f-t1.gif structure forms, which is identified as an Ag-free Si bilayer with additional Si adatoms. With further deposition, this structure is replaced by a distinct bilayer structure covered by Si trimers and Ag atoms. The formation of these bilayers follows counterintuitive dynamics: they are partially inserted within the Ag substrate and form by expelling, from the underlying substrate, the atoms that reinsert below the adjacent silicene layer. The growth is therefore characterized by an unexpected “surfactant competition” between Ag and silicene: while silicene is a metastable surfactant for the Ag(111) surface, Ag plays the role of a surfactant for thicker diamond-like Si islands. In spite of being thermodynamically unfavoured, the silicene monolayer is, thus, a remarkably stable structure because of the high kinetic barrier for the growth of thicker layers.

Graphical abstract: The mechanism for the stabilization and surfactant properties of epitaxial silicene

Supplementary files

Article information

Article type
Paper
Submitted
13 Sep 2017
Accepted
21 Dec 2017
First published
22 Dec 2017

Nanoscale, 2018,10, 2291-2300

The mechanism for the stabilization and surfactant properties of epitaxial silicene

A. Curcella, R. Bernard, Y. Borensztein, M. Lazzeri and G. Prévot, Nanoscale, 2018, 10, 2291 DOI: 10.1039/C7NR06833F

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