title: Large-scale uniform bilayer graphene prepared by vacuum graphitization of 6H-SiC(0001) substrates.
abstract: We report on the preparation of large-scale uniform bilayer graphenes on nominally flat Si-polar 6H-SiC(0001) substrates by flash annealing in ultrahigh vacuum. The resulting graphenes have a single thickness of one bilayer and consist of regular terraces separated by the triple SiC bilayer steps on the 6H-SiC(0001) substrates. In situ scanning tunneling microscopy reveals that suppression of pit formation on terraces and uniformity of SiC decomposition at step edges are the key factors to the uniform thickness. By studying the surface morphologies prepared under different annealing rates, it is found that the annealing rate is directly related to SiC decomposition, diffusion of the released Si/C atoms and strain relaxation, which together determine the final step structure and density of defects.
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
authors.forename: Qingyan
authors.initials: Q
authors.lastname: Wang
authors.forename: Wenhao
authors.initials: W
authors.lastname: Zhang
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
authors.forename: Ke
authors.initials: K
authors.lastname: He
authors.forename: Xucun
authors.initials: X
authors.lastname: Ma
authors.forename: Qikun
authors.initials: Q
authors.lastname: Xue