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Proceedings Paper

Ultrafast carrier dynamics of epitaxial silicene
Author(s): Eugenio Cinquanta; Guido Fratesi; Stefano dal Conte; Carlo Grazianetti; Francesco Scotognella; Salvatore Stagira; Caterina Vozzi; Giovanni Onida; Alessandro Molle
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Paper Abstract

The recent integration of silicene in field-effect transistors (FET) opened new challenges in the comprehension of the chemical and physical properties of this elusive two-dimensional allotropic form of silicon. Intense efforts have been devoted to the study of the epitaxial Silicene/Ag(111) system in order to elucidate the presence of Dirac fermion in analogy with graphene; strong hybridization effects in silicene superstructures on silver have been invoked as responsible for the disruption of π and π* bands. In this framework, the measured ambipolar effect in silicene-based FET characterized by a relatively high mobility, points out to a complex physics at the silicene-silver interface, demanding for a deeper comprehension of its details on the atomic scale. Here we elucidate the role of the metallic support in determining the physical properties of the Si/Ag interface, by means of optical techniques combined with theoretical calculations of the optical response of the supported system. The silicene/Ag(111) spectra, which turn out to be strongly non-additive, are analyzed in the framework of theoretical density functional based calculations allowing us to single out contributions arising from different localization. Electronic transitions involving silver states are found to provide a huge contribution to the optical absorption of silicene on silver, compatible with a strong Si-Ag hybridization. The results point to a dimensionality-driven peculiar dielectric response of the two-dimensional-silicon/silver interface, which is confirmed by means of Transient-Reflectance spectroscopy. The latter shows a metallic-like carrier dynamics, (both for silicene and amorphous silicon), hence providing an optical demonstration of the strong hybridization arising in silicene/Ag(111) systems.

Paper Details

Date Published: 23 February 2017
PDF: 8 pages
Proc. SPIE 10102, Ultrafast Phenomena and Nanophotonics XXI, 101020J (23 February 2017); doi: 10.1117/12.2252009
Show Author Affiliations
Eugenio Cinquanta, Lab. MDM, IMM, CNR (Italy)
Guido Fratesi, Univ. degli Studi di Milano (Italy)
European Theoretical Spectroscopy Facility (Italy)
Stefano dal Conte, Istituto di Fotonica e Nanotecnologie, CNR (Italy)
Politecnico di Milano (Italy)
Carlo Grazianetti, Lab. MDM, IMM, CNR (Italy)
Francesco Scotognella, Politecnico di Milano (Italy)
Salvatore Stagira, Politecnico di Milano (Italy)
Caterina Vozzi, Istituto di Fotonica e Nanotecnologie, CNR (Italy)
Giovanni Onida, Univ. degli Studi di Milano (Italy)
European Theoretical Spectroscopy Facility (Italy)
Alessandro Molle, Lab. MDM, IMM, CNR (Italy)

Published in SPIE Proceedings Vol. 10102:
Ultrafast Phenomena and Nanophotonics XXI
Markus Betz; Abdulhakem Y. Elezzabi, Editor(s)

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