From Silicene to Half-Silicane by Hydrogenation

TL;DR

This paper demonstrates the synthesis of half-silicane by hydrogenating specific silicene phases on Ag(111), revealing a perfect 1x1 structure with potential for novel 2D silicon-based materials.

Contribution

It introduces a method to produce half-silicane from silicene, clarifies the structure of the (2r3x2r3)R30° phase, and discusses the formation mechanism using first principles calculations.

Findings

Half-silicane was successfully produced on Ag(111).

Only the (2r3x2r3)R30° phase yields half-silicane.

The phase involves a complete silicene-1x1 lattice, not defective fragments.

Abstract

Graphane is graphene fully hydrogenated from both sides, forming a 1x1 structure, where all C atoms are in sp3 configuration. In silicene, the Si atoms are in a mix-sp2/sp3 configuration, it is therefore natural to imagine silicane in analogue to graphane. However, monoatomic silicene sheet grown on substrates generally reconstructs into different phases, and only partially hydrogenated silicene with reconstructions had been reported before. In this report we produce half-silicane, where one Si sublattice is fully H-saturated and the other sublattice is intact, forming a perfect 1x1 structure. By hydrogenating various silicene phases on Ag(111) substrate, we found that only the (2r3x2r3)R30{\deg} phase can produce half-silicane. Interestingly, this phase was previous considered to be a highly defective or incomplete silicene structure. Our results indicate that the structure of (2r3x2r3)R30{\deg} phase involves a complete silicene-1x1 lattice instead of defective fragments, and the formation mechanism of half-silicane was discussed with the help of first principles calculations.