Extended Data Fig. 3: Ultraflat graphene on the Cu(111)/sapphire wafer.
From: Uniform thin ice on ultraflat graphene for high-resolution cryo-EM
a, A large-area OM image of UFG on the wafer-scale Cu(111)/sapphire. Inset: the high-magnification OM image shows that no rolling lines were observed on the Cu(111)/sapphire. b, XRD pattern of Cu(111)/sapphire, proving the single-crystal Cu(111) film on the sapphire(α-Al2O3). c, White light interference (WLI) showing the ultraflat surface of graphene film on the Cu(111)/sapphire. d, Typical AFM images revealing the atomically flat graphene surface from the marked regions in (a). No step bunches and wrinkles were observed. e, Height profiles along the green lines in (d), showing that the maximum height variations of UFG are ±1 nm at a lateral scale of 5 μm. Scale bars, 1 μm. Source data are provided as a Source Data file.
