Electronic structure and the minimum conductance of a graphene layer on SiO2 from density-functional methods.

TL;DR

This study uses density-functional methods to analyze how SiO2 substrates influence the electronic structure and minimal conductance of graphene layers, providing insights into substrate effects and conduction mechanisms.

Contribution

It introduces realistic models of SiO2-supported graphene and investigates substrate-charge effects and minimal conductance states through density-functional calculations.

Findings

Substrate charge affects electronic band behavior near the Fermi level.

Equilibrium distance of graphene varies with substrate interaction.

Wavy graphene models help understand minimal conducting states.

Abstract

The effect of the SiO$_2$ substrate on a graphene film is investigated using realistic but computationally convenient energy-optimized models of the substrate supporting a layer of graphene. The electronic bands are calculated using density-functional methods for several model substrates. This provides an estimate of the substrate-charge effects on the behaviour of the bands near $E_F$, as well as a variation of the equilibrium distance of the graphene sheet. A model of a wavy graphene layer is examined as a possible candidate for understanding the nature of the minimally conducting states in graphene.