March 24, 2011

Epitaxial silicene formed on single-crystalline ZrB2 thin Films: structure and electronic properties

The experimental realization of extended, two-dimensional sheets of silicene, the silicon counterpart of graphene, has been elusive so far.

Researchers have demonstrated that such a two-dimensional, epitaxial honeycomb Si layer forms through surface segregation on a metallic zirconium diboride (ZrB2) Film grown itself epitaxially on Si(111). The honeycomb Si layer uniformly covers the ZrB2(0001) surface forming a (2£2) reconstruction. Surface-sensitive core-level photoelectron spectroscopy performed using a photon energy of 130 eV identifies Si atoms in different chemical states that are either in contact with Zr atoms or not, con¯rming details of the slightly-buckled honeycomb structure obtained through scanning tunneling microscopy. Angle resolved ultraviolet photoelectron spectra reflect surface electronic states related to the predicted band structure of slightly-buckled, free standing silicene together with those of the uppermost Zr layer



Last year, Guy Lelay created the first-ever silicene ribbons. Le Lay described these 1.6-nanometer wide stripes of honeycombed atoms, grown on top of silver, in the June 28 Applied Physics Letters.

“These ribbons can be more than a hundred nanometers long, perhaps micrometers,” Le Lay says.

New data from Le Lay’s group, also presented at the physical society meeting, suggests that silicene and graphene share not only a similar structure, but possibly similar electronic properties. Spectroscopic techniques provided evidence that silicene contains a Dirac cone — the entity that intrigues scientists because it allows electrons to move very quickly through graphene, which makes graphene a promising material for flexible electronics.

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