Self healing of vacancy defects in single layer graphene and silicene

TL;DR

This study investigates the atomistic mechanisms behind the self-healing of vacancy defects in graphene and silicene using first principles calculations, revealing how adatoms and reconstruction affect their properties.

Contribution

It provides detailed insights into the healing processes of vacancy defects in graphene and silicene, including the role of adatoms and atomic rebonding, which was previously not well understood.

Findings

Vacancy defects in graphene heal perfectly under external atom supply.

Silicene can form Stone-Wales defects during vacancy healing.

Reconstruction alters electronic and magnetic properties of both materials.

Abstract

Self healing mechanisms of vacancy defects in graphene and silicene are studied using first principles calculations. We investigated host adatom adsorption, diffusion, vacancy formation and revealed atomistic mechanisms in the healing of single, double and triple vacancies of single layer graphene and silicene. Silicon adatom, which is adsorbed to silicene at the top site forms a dumbbell like structure by pushing one Si atom underneath. The asymmetric reconstruction of the single vacancy in graphene is induced by the magnetization through the rebonding of two dangling bonds and acquiring a significant magnetic moment through remaining unsaturated dangling bond. In silicene, three two-fold coordinated atoms surrounding the single vacancy become four-fold coordinated and nonmagnetic through rebonding. The energy gained through new bond formation becomes the driving force for the reconstruction. Under the external supply of host atoms, while the vacancy defects of graphene heal perfectly, Stone-Wales defect can form in the course of healing of silicene vacancy. The electronic and magnetic properties of suspended, single layer graphene and silicene are modified by reconstructed vacancy defects.