  The remarkable properties of graphene stem from its two-dimensional (2D)
structure, with a linear dispersion of the electronic states at the corners of
the Brillouin zone (BZ) forming a Dirac cone. Since then, other 2D materials
have been suggested based on boron, silicon, germanium, phosphorus, tin, and
metal di-chalcogenides. Here, we present an experimental investigation of a
single silicon layer on Au(111) using low energy electron diffraction (LEED),
high resolution angle-resolved photoemission spectroscopy (HR-ARPES), and
scanning tunneling microscopy (STM). The HR-ARPES data show compelling evidence
that the silicon based 2D overlayer is responsible for the observed linear
dispersed feature in the valence band, with a Fermi velocity of v_F ~10^(+6)
m.s^(-1) comparable to that of graphene. The STM images show extended and
homogeneous domains, offering a viable route to the fabrication of
silicene-based opto-electronic devices.
