Epitaxial Growth of Large-area Bilayer Graphene on Ru(0001)

TL;DR

This paper reports the epitaxial growth of large-area bilayer graphene on Ru(0001), revealing strain differences between layers, moire pattern formation, and intrinsic electronic properties akin to free-standing graphene.

Contribution

It demonstrates a method for growing large-area bilayer graphene with specific stacking and strain characteristics on Ru(0001).

Findings

Bottom layer is stretched by 1.2%

Moire pattern with ~21.5 nm periodicity observed

BG exhibits properties similar to intrinsic free-standing graphene

Abstract

Large-area bilayer graphene (BG) is grown epitaxially on Ru(0001) surface and characterized by low temperature scanning tunneling microscopy. The lattice of the bottom layer of BG is stretched by 1.2%, while strain is absent from the top layer. The lattice mismatch between the two layers leads to the formation of a moire pattern with a periodicity of ~21.5 nm and a mixture of AA- and AB-stacking. The root3 x root3 superstructure around atomic defects is attributed to the inter-valley scattering of the delocalized pi-electrons, demonstrating that the as-grown BG behaves like intrinsic free-standing graphene.