Optical properties of silicene, Si/Ag(111), and Si/Ag(110)

We present a state-of-the-art study of the optical properties of free-standing silicene and of single-layer Si one- and two-dimensional (1D and 2D) nanostructures supported on Ag(110) and Ag(111) substrates. Ab initio simulations of reflectance anisotropy spectroscopy (RAS) and surface differential...

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Bibliographic Details
Published in:Physical review. B 2018-05, Vol.97 (19), Article 195407
Main Authors: Hogan, C., Pulci, O., Gori, P., Bechstedt, F., Martin, D. S., Barritt, E. E., Curcella, A., Prevot, G., Borensztein, Y.
Format: Article
Language:English
Subjects:
Absorption spectra
Anisotropy
Bonding strength
Computer simulation
Mathematical analysis
Optical communication
Optical properties
Reflectance
Reflectance anisotropy spectroscopy
Response functions
Silicene
Silicon
Silver
Spectrum analysis
Substrates
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Summary:We present a state-of-the-art study of the optical properties of free-standing silicene and of single-layer Si one- and two-dimensional (1D and 2D) nanostructures supported on Ag(110) and Ag(111) substrates. Ab initio simulations of reflectance anisotropy spectroscopy (RAS) and surface differential reflectivity spectroscopy (SDRS) applied to the clean Ag surface and Si/Ag interfaces are compared with new measurements. For Si/Ag(110), we confirm a pentagonal nanoribbon geometry, strongly bonded to the substrate, and rule out competing zigzag chain and silicenelike models. For Si/Ag(111), we reproduce the main experimental features and isolate the optical signal of the epitaxial silicene overlayer. The absorption spectrum of a silicene sheet computed including excitonic and local field effects is found to be quite similar to that calculated within an independent particle approximation and shows strong modifications when adsorbed on a Ag substrate. Important details of the computational approach are examined and the origins of the RAS and SDRS signals are explained in terms of the interface and substrate response functions. Our study does not find any evidence for Si adlayers that retain the properties of freestanding silicene.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.97.195407