1212.5422 (E. Cinquanta et al.)

Raman spectrum of epitaxial silicene    [PDF]

E. Cinquanta, E. Scalise, D. Chiappe, C. Grazianetti, B. van den Broek, M. Houssa, M. Fanciulli, A. Molle

In the present manuscript we report the first Raman identification of silicene by combining visible Raman spectroscopy, Scanning Tunneling Microscopy and ab-initio density functional theory (DFT) calculations. We demonstrate how the Raman fingerprint of epitaxial silicene is strictly connected to the geometrical arrangement of the hexagonal silicene lattice, which in turn is strongly determined by the silicene/substrate interaction. Remarkably, next to the presence of the double degenerate E2g mode, typical for honeycomb lattices, the non-uniform bond length and the non-symmetric buckling in the silicene layer introduce an intrinsic disorder in the honeycomb lattice which provides, even for defect-free domains, broad and intense disorderactivated peaks. Furthermore, by combining in-situ X-Ray Photoemission Spectroscopy and ex-situ Raman spectroscopy, we show how silicene is highly reactive to atmospheric gases thus highlighting how the presence of a capping layer is necessary in order to perform any ex-situ characterizations.

View original: http://arxiv.org/abs/1212.5422