Weak localization scattering lengths in epitaxial, and CVD graphene

TL;DR

This study investigates weak localization effects in epitaxial and CVD graphene across a wide carrier density range, analyzing scattering lengths and their dependence on carrier density using magnetic field measurements.

Contribution

It provides a detailed analysis of scattering lengths in graphene and demonstrates the measurement conditions needed to avoid hot-electron artifacts.

Findings

L_phi shows no significant dependence on carrier density.

L_i weakly decreases with increasing carrier density.

L_* follows a n^(-1/4) dependence.

Abstract

Weak localization in graphene is studied as a function of carrier density in the range from 1 x $10^{11}$\,cm$^{-2}$ to 1.43 x $10^{13}$\,cm$^{-2}$ using devices produced by epitaxial growth onto SiC and CVD growth on thin metal film. The magnetic field dependent weak localization is found to be well fitted by theory, which is then used to analyse the dependence of the scattering lengths L$_\varphi$, L$_i$, and L$_*$ on carrier density. We find no significant carrier dependence for L$_\varphi$, a weak decrease for L$_i$ with increasing carrier density just beyond a large standard error, and a n$^{-\frac{1}{4}}$ dependence for L$_*$. We demonstrate that currents as low as 0.01\,nA are required in smaller devices to avoid hot-electron artefacts in measurements of the quantum corrections to conductivity.