Transfer of Graphene with Protective Oxide Layers

TL;DR

This paper presents a novel graphene transfer method using a protective oxide layer grown by ALD, reducing residues and improving transfer quality compared to traditional polymer-based methods.

Contribution

It introduces a new transfer technique employing ALD-grown oxide layers and thin polymers, enhancing graphene transfer with fewer residues and better film quality.

Findings

Hafnia provides more uniform and defect-free coatings than alumina.

The oxide-graphene transfer process reduces polymer residues.

Optical transmission of coated graphene is maintained effectively.

Abstract

Transfer of graphene, grown by Chemical Vapor Deposition (CVD), to a substrate of choice, typically involves deposition of a polymeric layer (typically, poly(methyl methacrylate, PMMA or polydimethylsiloxane, PDMS). These polymers are quite hard to remove without leaving some residues behind. Here we study a transfer of graphene with a protective thin oxide layer. The thin oxide layer is grown by Atomic Deposition Layer (ALD) on the graphene right after the growth stage on Cu foils. One can further aid the oxide-graphene transfer by depositing a very thin polymer layer on top of the composite (much thinner than the usual thickness) following by a more aggressive polymeric removal methods, thus leaving the graphene intact. We report on the nucleation growth process of alumina and hafnia films on the graphene, their resulting strain and on their optical transmission. We suggest that hafnia is a better oxide to coat the graphene than alumina in terms of uniformity and defects.