Fig. 2

Different oxidation behaviors of various microscopic graphene defects in graphene islands depending on variables. Representative SEM images of Gr islands grown on a Cu foil at 1000 °C for 1 min a before and b after annealing at ~200 °C for 70 min in air (scale bar=3 µm). c A typical Raman D/G map image of the as-synthesized Gr islands transferred onto SiO₂/Si (scale bar=3 µm). d Typical EBSD map images of the Cu foil after Gr islands were grown at 1000 °C, followed by the annealing process at ~200 °C for 120 min in air (scale bar=50 µm). The EBSD data show that the Cu foils consist of grains mostly with orientations of approximately (100) (upper) and, in some regions, grains with orientations of (111) and (101), as well as high-index orientations (bottom). e–i Representative SEM images of the annealed Gr islands grown on Cu grains with an orientation of e, f (100), g (101), h (111), and i the boundary region between (100) and (111) (indicated by the white-dotted square in Fig. 2d). Scale bars, 2 µm e–h, 10 µm i. j A typical Raman D/G map image of the Gr islands grown on a Cu(111) grain transferred onto SiO₂/Si (scale bar=2 µm). k–m OM images of the Gr islands grown on Cu(100) grains after annealing at ~200 °C for 120 min under various CVD growth conditions. The Gr islands were grown k at ~1050 °C for 30 s under CH₄ (10 sccm) and H₂ (5 sccm), l at ~1000 °C for 30 s under CH₄ (10 sccm) and H₂ (20 sccm), and m at ~1,000 °C for 3 min under CH₄ (2 sccm) and H₂ (5 sccm). The scale bars represent 10 μm