Uniform wafer-scale synthesis of graphene on evaporated Cu (111) film with quality comparable to exfoliated monolayer

TL;DR

This paper reports a method for synthesizing high-quality, uniform monolayer graphene on wafer-scale evaporated Cu (111) films, achieving defect levels comparable to exfoliated graphene, with potential for flexible electronics.

Contribution

The study introduces a scalable process for growing uniform monolayer graphene on oxidized Si wafers using phase-transformed copper films and hydrogen annealing, with high mobility results.

Findings

>97% wafer coverage of graphene

>95% defect-negligible across the wafer

Carrier mobility ~4,930 cm2/Vs in graphene transistors

Abstract

Monolayer graphene has been grown on crystallized Cu (111) films on standard oxidized Si 100 mm wafers. The monolayer graphene demonstrates high uniformity (>97% coverage), with immeasurable defects (>95% defect-negligible) across the entire wafer. Key to these results is the phase transition of evaporated copper films from amorphous to crystalline at the growth temperature as corroborated by X-ray diffraction and electron backscatter diffraction. Noticeably, phase transition of copper film is observed on technologically ubiquitous oxidized Si wafer where the oxide is a standard amorphous thermal oxide. Ion mass spectroscopy indicates that the copper films can be purposely hydrogen-enriched during a hydrogen anneal which subsequently affords graphene growth with a sole carbonaceous precursor for low defect densities. Owing to the strong hexagonal lattice match, the graphene domains align to the Cu (111) domains, suggesting a pathway for increasing the graphene grains by maximizing the copper grain sizes. Fabricated graphene transistors on a flexible polyimide film yield a peak carrier mobility ~4,930 cm2/Vs.