The Alignment Dependent Properties and Applications of Graphene Moiré Superstructures on Ru(0001) Surface
The moiré superstructure of graphene on a lattice-mismatched metal substrate has profound effects on the electronic properties of the graphene and can be used for many applications. Here, we propose to systematically tune the graphene moiré superstructure on the Ru(0001) surface by rotating the graphene layer. Our study reveals two kinds of graphene moiré superstructures: (i) the ultra-flat graphene layers with height variations less than 0.1 Å for rotation angles greater than 20 degree, which has the same structural and electronic properties everywhere, and (ii) the highly corrugated graphene moiré superstructures with height variations from 0.4 to 1.6 Å for rotation angles less than 20 degrees, of which the electronic properties are highly modulated by the interaction with the substrate. Moreover, these rotated graphene moiré superstructures can serve templates to produce the matrices of size-tunable metal clusters from a few to ~ 100 atoms. This study reveals the causes of the structural fluctuation of graphene moiré superstructures on transition metal surface and suggested a pathway toward tuning graphene’s electronic properties for various applications.