American Chemical Society
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Optical Conductivity of Two-Dimensional Silicon: Evidence of Dirac Electrodynamics

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journal contribution
posted on 2018-10-26, 00:00 authored by Carlo Grazianetti, Stefania De Rosa, Christian Martella, Paolo Targa, Davide Codegoni, Paola Gori, Olivia Pulci, Alessandro Molle, Stefano Lupi
The exotic electrodynamics properties of graphene come from the linearly dispersive electronic bands that host massless Dirac electrons. A similar behavior was predicted to manifest in freestanding silicene, the silicon counterpart of graphene, thereby envisaging a new route for silicon photonics. However, the access to silicene exploitation in photonics was hindered so far by the use of optically inappropriate substrates in experimentally realized silicene. Here we report on the optical conductivity of silicon nanosheets epitaxially grown on optically transparent Al2O3(0001) from a thickness of a few tens of nanometers down to the extreme two-dimensional (2D) limit. When a 2D regime is approached, a Dirac-like electrodynamics can be deduced from the observation of a low-energy optical conductivity feature owing to a silicene-based interfacing to the substrate.