Investigating the CVD synthesis of graphene on Ge(100): towards layer by layer growth

TL;DR

This study explores how adjusting process gas flows in CVD can control the growth of high-quality graphene on Ge(100), achieving layer-by-layer growth and homogeneous monolayer graphene suitable for CMOS applications.

Contribution

It demonstrates the ability to control graphene growth regimes on Ge(100) via process gas flow variations, enabling layer-by-layer synthesis of high-quality graphene.

Findings

Different growth regimes (nanoribbons, monolayer, multilayer) are achieved by varying precursor flow.

Layer-by-layer growth regime identified and optimized.

Homogeneous monolayer graphene with high 2D/G ratio achieved.

Abstract

Germanium is emerging as the substrate of choice for the growth of graphene in CMOS-compatible processes. For future application in next generation devices the accurate control over the properties of high-quality graphene synthesized on Ge surfaces, such as number of layers and domain size, is of paramount importance. Here we investigate the role of the process gas flows on the CVD growth of graphene on Ge(100). The quality and morphology of the deposited material is assessed by using microRaman spectroscopy, x-ray photoemission spectroscopy, scanning electron and atomic force microscopies. We find that by simply varying the carbon precursor flow different growth regimes - yielding to graphene nanoribbons, graphene monolayer and graphene multilayer - are established. We identify the growth conditions yielding to a layer-by-layer growth regime and report on the achievement of homogeneous monolayer graphene with an average intensity ratio of 2D and G bands in the Raman map larger than 3.