Flat Zigzag Silicene Nanoribbon with Be Bridge

The emergence of flat one- and two-dimensional materials, such as graphene and its nanoribbons, has promoted the rapid advance of the current nanotechnology. Silicene, a silicon analogue of graphene, has the great advantage of its compatibility with the present industrial processes based on silicon nano- technology. The most significant issue for silicene is instability in the air due to the nonplanar puckered (buckled) structure. Another critical problem is that silicene is usually synthesized by epitaxial growth on a substrate, which strongly affects the pi conjugated system of silicene. The fabrication of free-standing silicene with a planar configuration has long been pursued. Here, we report the strategy and design to realize the flat zigzag silicene nanoribbon. We theoretically investigated the stability of various silicene nanoribbons with substituents at the zigzag edges and found that zigzag silicene nanoribbons with beryllium (Be) bridges are very stable in a planar configuration. The obtained zigzag silicene nanoribbon has an indirect negative band gap and is nonmagnetic unlike the magnetic buckled silicene nanoribbons with zigzag edges. The linearly dispersive behavior of the pi and pi* bands associated with the out-of-plane 3p(Si) and 2p(Be) orbitals is clearly observed, showing the existence of a Dirac point slightly above the Fermi level. We also observed that spin-orbit coupling induces a gap opening at the Dirac point.

Automated summary

The emergence of two-dimensional materials like graphene has advanced nanotechnology rapidly. Silicene, a silicon analogue of graphene, has the advantage of compatibility with silicon nano-technology processes but faces issues of instability and synthesis methods affecting its structure. Researchers have now successfully designed flat zigzag silicene nanoribbons, showing stable properties with unique band gaps and dispersive behavior.