Formation of Silicene on Ultrathin Pb(111) Films

Abstract

The great success of graphene has spurred huge interest in two-dimensional honeycomb lattices of post-carbon group-14 atoms, namely, Xenes. However, the synthesis of Xenes on supporting substrates remains a big challenge due to the problem of Xene–substrate interaction. Recently, Pb(111) layers have been proposed as potential supports for silicene, the silicon follower of graphene. Using scanning tunneling microscopy and spectroscopy supported by ab initio density functional theory calculations, we reveal the epitaxial growth of silicene nanosheets on ultrathin Pb(111) films. Direct deposition of silicon on the Pb substrate results in two different discrete Si phases: √3 × √3 covered and 1 × 1 uncovered silicene structures. Scanning tunneling microscopy and spectroscopy measurements clearly display an atomically resolved low-buckled silicene honeycomb lattice in the uncovered phase. The covered phase represents the case of the Si(111)√3 × √3–Pb reconstruction on the thinnest Si substrate in the form of a single silicene layer.