"Graphene-like bilayer hexagonal silicon polymorph" by Jaeil Bai, Hideki Tanaka et al.

Article Title

Graphene-like bilayer hexagonal silicon polymorph

Authors

Jaeil Bai, Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
Hideki Tanaka, Department of Chemistry, Okayama University, Okayama 700-8530, Japan
Xiao Cheng Zeng, Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA

Keywords

Bilayer hexagonal silicon, slit pore, semimetal, two-dimensional polymorph

Abstract

We present molecular dynamics simulation evidence for a freezing transition from liquid silicon to quasi-two- dimensional (quasi-2D) bilayer silicon in a slit nanopore. This new quasi-2D polymorph of silicon exhibits a bilayer hexagonal structure in which the covalent coordination number of every silicon atom is four. Quantum molecular dynamics simulations show that the stand-alone bilayer silicon (without the confinement) is still stable at 400 K. Electronic band-structure calculations suggest that the bilayer hexagonal silicon is a quasi-2D semimetal, similar to a graphene monolayer, but with an indirect zero band gap.