Fig. 4
From: Oxidation behavior of graphene-coated copper at intrinsic graphene defects of different origins
Control experiments to elucidate the origin and process of Cu oxidation through a polycrystalline graphene barrier. Typical SEM images of fully-grown Gr/Cu samples annealed at ~200 °C a for 120 min under vacuum (P ≈ 10−3 Torr), b for 120 min in a pure O2 atmosphere (P ≈ 150 Torr), c for 120 min in ambient air (RH ≈ 30–40%), d for 60 min in a wet-O2 atmosphere (RH ≈ 80%), and e for 60 min in a wet-N2 atmosphere (RH ≈ 50%). The scale bars represent 10 µm. f, g A comparison of the HR-XPS O 1s peaks and of the chemical compositions of the Gr/Cu samples depending on the annealing temperature and time in ambient air. h Representative plan-view HR-TEM image of a Gr film transferred onto a TEM support grid (scale bar: 2 nm). The inset is an atomic-resolution image of a GB of Gr, indicated by a yellow square (scale bar=0.5 nm). i Plot of the average width of the oxidation line feature as a function of annealing time up to 48 h based on the SEM observation. Error bars represent ±1 standard deviation, obtained from 100 different points in each sample
