Carrier scattering, mobilities and electrostatic potential in mono-, bi- and tri-layer graphenes

TL;DR

This study systematically investigates how carrier density and temperature affect Hall mobility in mono-, bi-, and tri-layer graphene, revealing different scattering mechanisms and electrostatic potential variations across layers.

Contribution

It provides a comprehensive analysis of mobility and electrostatic potential in layered graphene, highlighting layer-dependent scattering mechanisms and temperature effects.

Findings

Mobility decreases with carrier density in mono-layer graphene.

Mobility increases with carrier density in bi- and tri-layer graphene.

Temperature affects mobility differently depending on layer number, due to substrate phonon screening and Coulomb scattering.

Abstract

The carrier density and temperature dependence of the Hall mobility in mono-, bi- and tri-layer graphene has been systematically studied. We found that as the carrier density increases, the mobility decreases for mono-layer graphene, while it increases for bi-layer/tri-layer graphene. This can be explained by the different density of states in mono-layer and bi-layer/tri-layer graphenes. In mono-layer, the mobility also decreases with increasing temperature primarily due to surface polar substrate phonon scattering. In bi-layer/tri-layer graphene, on the other hand, the mobility increases with temperature because the field of the substrate surface phonons is effectively screened by the additional graphene layer(s) and the mobility is dominated by Coulomb scattering. We also find that the temperature dependence of the Hall coefficient in mono-, bi- and tri-layer graphene can be explained by the formation of electron and hole puddles in graphene. This model also explains the temperature dependence of the minimum conductance of mono-, bi- and tri-layer graphene. The electrostatic potential variations across the different graphene samples are extracted.