First-principles study on competing phases of silicene: Effect of substrate and strain

TL;DR

This study uses first-principles calculations to explore how substrate effects and strain influence the stability and electronic structure of silicene phases, revealing a substrate-stabilized planar-like phase under specific conditions.

Contribution

It identifies a stable reconstructed silicene phase on ZrB₂(0001) surface, highlighting substrate and strain effects on silicene's structural preferences and stability.

Findings

The planar-like silicene phase is stable on ZrB₂(0001) surface.

Substrate interactions favor the planar-like phase over buckled forms.

Strain influences the relative stability of silicene phases.

Abstract

The stability and electronic structure of competing silicene phases under in-plane compressive stress, either free-standing or on the ZrB$_2$(0001) surface, has been studied by first-principles calculations. A particular ($\sqrt{3}\times\sqrt{3}$)-reconstructed structural modification was found to be stable on the ZrB$_2$(0001) surface under epitaxial conditions. In contrast to the planar and buckled forms of free-standing silicene, in this "planar-like" phase, all but one of the Si atoms per hexagon reside in a single plane. While without substrate, for a wide range of strain, this phase is energetically less favorable than the buckled one, it is calculated to represent the ground state on the ZrB$_2$(0001) surface. The atomic positions are found to be determined by the interactions with the nearest neighbor Zr atoms competing with Si-Si bonding interactions provided by the constraint of the honeycomb lattice.