Fig. 4: AFM images and C1s XPS spectra of samples with argon cooling.
From: Self-limited monolayer graphene growth on SiC with propane-hydrogen CVD
Argon cooling is achieved by interrupting simultaneously heating, propane and hydrogen flows. The morphology is smooth, albeit discontinuous, on the sample with a growth time of 4 min (a), and perfectly smooth, except the SiC steps, on the sample with a growth time of 15 min (b). The XPS spectra (c) are that of graphene on a buffer layer, hence proving that argon cooling allows the suppression of hydrogen effects during this step. Vertical scale is Δz = 5 nm for both AFM images, and the XPS spectra are normalized and shifted with respect to the SiC peak.
