Abstract
A comprehensive picture of the initial stages of silicene growth on graphite is drawn. Evidence is shown that quasiparticle interferences play a crucial role in the formation of the observed silicene configurations. We propose, on one hand, that the charge modulations caused by those quantum interferences serve as templates and guide the incoming Si atoms to self-assemble to the unique \(\left( {\sqrt 3 \times \sqrt 3 } \right)\)R30° honeycomb atomic arrangement. On the other hand, their limited extension limits the growth to about 150 Si atoms under our present deposition conditions. The here proposed electrostatic interaction finally explains the unexpected stability of the observed silicene islands over time and with temperature. Despite the robust guiding nature of those quantum interferences during the early growth phase, we demonstrate that the window of experimental conditions for silicene growth is quite narrow, making it an extremely challenging experimental task. Finally, it is shown that the experimentally observed three-dimensional silicon clusters might very well be the simple result of the end of the silicene growth resulting from the limited extent of the quasi-particle interferences.
Highlights
Since the Nobel-prize winning discovery of graphene, much research has been dedicated to alternative two-dimensional (2D) materials that might overcome the principle drawback of graphene of being gapless [1]
We would like to remind the reader here that the calculations by Cai et al are based on the assumption of an infinite silicene/graphene system and that our present experimental observations are limited to nano islands whose size never exceeds about 150 Si atoms; i.e., we have to take into consideration the very early stages of the silicene growth on graphite
For this initial phase of the silicene growth, the van der Waals interaction between Si atoms and the graphene substrate is of crucial importance
Summary
Since the Nobel-prize winning discovery of graphene, much research has been dedicated to alternative two-dimensional (2D) materials that might overcome the principle drawback of graphene of being gapless [1]. One of these materials is the silicon analogue, named silicene. The corresponding Raman analysis reveals the presence of a resonance located at 542.5 cm-1 This position of the Raman peak perfectly fits the atomic vibration of Si atoms in a (√3×√3)R30° honeycomb silicene nano island deposited on HOPG, found by first-principles calculations. It cannot be explained by charge modulations. The formation of genuine silicene nano islands is strongly supported by a large body of evidence not restricted to STM measurements and ab initio calculations, but it finds confirmation by the direct measurement of the vibrational movement of Si atoms forming finite silicene nano islands
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