Quasi-Periodic Nanoripples in Graphene Grown by Chemical Vapor Deposition and Its Impact on Charge Transport

TL;DR

This paper reveals that quasi-periodic nanoripple arrays formed during CVD graphene growth limit charge mobility and increase resistance, highlighting the importance of controlling nanostructures for better electrical performance.

Contribution

It uncovers the impact of nanoripple arrays on charge transport in CVD graphene, providing new insights into growth and transfer process improvements.

Findings

Nanoripple arrays are formed during high-temperature CVD and wet transfer.

NRAs cause anisotropic charge transport due to electron-flexural phonon scattering.

Charge mobility and sheet resistance are limited by these nanostructures within a single grain.

Abstract

The technical breakthrough in synthesizing graphene by chemical vapor deposition methods (CVD) has opened up enormous opportunities for large-scale device applications. In order to improve the electrical properties of CVD graphene grown on copper (Cu-CVD graphene), recent efforts have focussed on increasing the grain size of such polycrystalline graphene films to 100 micrometers and larger. While an increase in grain size and hence, a decrease of grain boundary density is expected to greatly enhance the device performance, here we show that the charge mobility and sheet resistance of Cu-CVD graphene is already limited within a single grain. We find that the current high-temperature growth and wet transfer methods of CVD graphene result in quasi-periodic nanoripple arrays (NRAs). Electron-flexural phonon scattering in such partially suspended graphene devices introduces anisotropic charge transport and sets limits to both the highest possible charge mobility and lowest possible sheet resistance values. Our findings provide guidance for further improving the CVD graphene growth and transfer process.