Pure, $Si$ and $sp^3$-doped Graphene nanoflakes: a numerical study of density of states

TL;DR

This study investigates how doping graphene nanoflakes with silicon or $sp^3$-hybridized carbon atoms affects their electronic density of states, revealing transitions from semiconducting to conducting behavior.

Contribution

It introduces a numerical approach using a modified tight binding method to analyze the density of states in doped and undoped graphene nanoflakes, highlighting the effects of doping on electronic properties.

Findings

Pure nanoflakes are semiconducting due to armchair edges.

Doping induces metallic behavior by removing degeneracy.

Fermi levels of $ ext{pi}$ and $ ext{sigma}$ electrons do not align in small nanoflakes.

Abstract

We built graphene nanoflakes doped or not with $C$ atoms in the $sp^3$ hybridization or with $Si$ atoms. These nanoflakes are isolated, i.e. are not connected to any object (substrate or junction). We used a modified tight binding method to compute the $\pi$ and $\sigma$ density of states. The nanoflakes are semiconducting (due to the armchair geometry of their boundaries) when their are pure but the become conducting when doped because doping removes the degeneracy of the density of states levels. Moreover, we showed that the $\pi$ Fermi level and the Fermi level of both $\pi$ and $\sigma$ electrons are not superimposed for small isolated nanoflakes.