Mono-, bi- and tri- graphene layers deposited on conductive Au/Cr/SiO2/Si substrate studied by scanning tunnelling spectroscopy

TL;DR

This study uses scanning tunneling spectroscopy to analyze how gold substrates affect the electronic properties of mono-, bi-, and tri-layer graphene, revealing p-type doping and layer-dependent Fermi level shifts.

Contribution

It provides experimental evidence of substrate-induced doping effects on multiple graphene layers, aligning with theoretical predictions.

Findings

Gold substrate causes downward Fermi level shift in graphene.

P-type doping occurs due to hole donation from gold.

Fermi level shift decreases with increasing graphene layers.

Abstract

Graphene devices require electric contacts with metals, particularly with gold. Scanning tunneling spectroscopy studies of electron local density of states performed on mono-, bi- and tri- graphene layer deposited on metallic conductive Au/Cr/SiO2/Si substrate shows that gold substrate causes the Fermi level shift downwards which means that holes are donated by metal substrate to graphene which becomes p-type doped. These experimental results are in good accordance with recently published density function theory calculations. The estimated positions of the Dirac point show that the higher number of graphene layers the lower Fermi level shift is observed.