Hexagonal Boron Nitride assisted transfer and encapsulation of large area CVD graphene.

Viktoryia Shautsova,Lesley F Cohen,Nicola C G Black,Stefan A Maier,Adam M Gilbertson

doi:10.1038/srep30210

Viktoryia Shautsova, Lesley F Cohen + Show 3 more

Open Access

https://doi.org/10.1038/srep30210

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Abstract

We report a CVD hexagonal boron nitride (hBN-) assisted transfer method that enables a polymer-impurity free transfer process and subsequent top encapsulation of large-area CVD-grown graphene. We demonstrate that the CVD hBN layer that is utilized in this transfer technique acts as a buffer layer between the graphene film and supporting polymer layer. We show that the resulting graphene layers possess lower doping concentration, and improved carrier mobilities compared to graphene films produced by conventional transfer methods onto untreated SiO2/Si, SAM-modified and hBN covered SiO2/Si substrates. Moreover, we show that the top hBN layer used in the transfer process acts as an effective top encapsulation resulting in improved stability to ambient exposure. The transfer method is applicable to other CVD-grown 2D materials on copper foils, thereby facilitating the preparation of van der Waals heterostructures with controlled doping.

Highlights

By introducing the ODTS buffer layer (WT-Gr/SAM), we see a significant reduction in the doping variations (Fig. 3c), which is in a good agreement with previous results for graphene transferred on SAM-modified substrates[20,31]
The change in the absolute conductivity value is a combination of the change of carrier doping in the graphene film and any changes to the contact resistance, which is captured by two terminal electrical measurements
The hydrophobic SAM should be less susceptible to water or oxygen adsorbents[20,21,22,23], in this study we find that the wet transfer (WT)-Gr/SAM sample shows the most significant VD increase with time

Summary

Introduction

By introducing the ODTS buffer layer (WT-Gr/SAM), we see a significant reduction in the doping variations (Fig. 3c), which is in a good agreement with previous results for graphene transferred on SAM-modified substrates[20,31]. Since the CVD hBN layer was transferred using the conventional WT method, polymer residues present on the surface introduce additional doping variations in the WT-Gr/hBN sample.

Results

Conclusion