Electronic structure of stacking faults in hexagonal graphite

TL;DR

This study uses electronic structure calculations to analyze stacking faults in hexagonal graphite, revealing localized interface bands and their impact on local conductivity, with implications for understanding defect-related electronic properties.

Contribution

It provides a detailed comparison of two stacking fault types, their induced interface bands, and the effects of surface layer displacement on electronic states in graphite.

Findings

Both stacking fault types induce localized interface bands near K-M.

Stacking faults create peaks in the local density of states close to the Fermi energy.

Displacement of a surface layer induces a surface band near K-M.

Abstract

We present results of self-consistent, full-potential electronic structure calculations for slabs of hexagonal graphite with stacking faults and for slabs with one displaced surface layer. There are two types of stacking faults, which differ qualitatively in their chemical bonding picture. We find, that both types induce localized interface bands near the symmetry line K-M in the Brillouin zone and a related peak in the local density of states (LDOS) very close to the Fermi energy, which should give rise to a dominating contribution of the interface bands to the local conductivity at the stacking faults. In contrast, a clean surface does not host any surface bands in the energy range of the pi and sigma bands, and the LDOS near the surface is even depleted. On the other hand, displacement of even one single surface layer induces a surface band near K-M. A special role play p_z-bonded dimers (directed perpendicular to the layers) in the vicinity of one type of stacking faults. They produce a half-filled pair of interface states / interface resonances. The formation energy of both types of stacking faults and the surface energy are estimated.