Growth of large-area single- and bi-layer graphene by controlled carbon precipitation on polycrystalline Ni surfaces

TL;DR

This study demonstrates controlled growth of large-area single- and bi-layer graphene on polycrystalline Ni via atmospheric CVD, achieving high uniformity and large sizes suitable for practical applications.

Contribution

It introduces a method to produce large, uniform, high-quality graphene films with controlled thickness by optimizing CVD parameters and cooling rates.

Findings

Up to 87% of the film area is covered with 1-2 layer graphene.

Single layer regions constitute 5-11% of the total film.

Films as large as 1 in² were successfully transferred.

Abstract

We report graphene films composed mostly of one or two layers of graphene grown by controlled carbon precipitation on the surface of polycrystalline Ni thin films during atmospheric chemical vapor deposition(CVD). Controlling both the methane concentration during CVD and the substrate cooling rate during graphene growth can significantly improve the thickness uniformity. As a result, one- or two- layer graphene regions occupy up to 87% of the film area. Single layer coverage accounts for 5-11% of the overall film. These regions expand across multiple grain boundaries of the underlying polycrystalline Ni film. The number density of sites with multilayer graphene/graphite (>2 layers) is reduced as the cooling rate decreases. These films can also be transferred to other substrates and their sizes are only limited by the sizes of the Ni film and the CVD chamber. Here, we demonstrate the formation of films as large as 1 in2. These findings represent an important step towards the fabrication of large-scale high-quality graphene samples.