Charge transfer of edge states in zigzag silicene nanoribbons with Stone-Wales defects

TL;DR

This study explores how Stone-Wales defects affect the structural and electronic properties of silicene and its nanoribbons, revealing that edge defects significantly alter edge states and induce band gaps, with implications for electronic engineering.

Contribution

It provides a detailed first-principles analysis of how defect concentration and location influence silicene's electronic properties, especially at edges, which was not thoroughly studied before.

Findings

SW defects prefer edge locations due to lower formation energy.

Edge SW defects split degenerate edge states and open a sizable electronic gap.

Defects cause charge transfer between edges, perturbing electronic states.

Abstract

Stone-Wales (SW) defects are favorably existed in graphenelike materials with honeycomb lattice structure and potentially employed to change the electronic properties in band engineering. In this paper, we investigate structural and electronic properties of SW defects in bulk silicene and its nanoribbons as a function of their concentration using the methods of periodic boundary conditions with first-principles calculations. We first calculate the formation energy, structural properties, and electronic band structures of SW defects in bulk silicene, with dependence on the concentration of SW defects. Our results show a good agreement with available values from the previous first-principles calculations. The energetics, structural aspects, and electronic properties of SW defects with dependence on defect concentration and location in edge-hydrogenated zigzag silicene nanoribbons are obtained. For all calculated concentrations, the SW defects prefer to locate at the edge due to the lower formation energy. The SW defects at the center of silicene nanoribbons slightly influence on the electronic properties, whereas the SW defects at the edge of silicene nanoribbons split the degenerate edge states and induce a sizable gap, which depends on the concentration of defects. It is worth to find that the SW defects produce a perturbation repulsive potential, which leads the decomposed charge of edge states at the side with defect to transfer to the other side without defect.