Growth mechanism of graphene on Cu(111) substrates studied by in-situ photoelectron spectroscopy

Ogawa, Shuichi*; Yamada, Takatoshi*; Ishizuka, Shinji*; Yoshigoe, Akitaka ; Hasegawa, Masataka*; Teraoka, Yuden; Takakuwa, Yuji*

The behavior of C atoms in vacuum annealing/cooling processes for a graphene/Cu(111) has been investigated using synchrotron radiation photoelectron spectroscopy (SR-XPS). The sample structure is graphene/Cu(111)/AlO(0001), in which graphene was grown by a thermal CVD method at 1273 K. The C 1s, O 1s, and Cu 3s SR-XPS spectra were measured in situ during annealing/cooling in vacuum. The graphene coverage at a low temperature region below 873 K is almost 1 monolayer (ML), but it decreased with increasing temperature. At 1223 K, the coverage reached 0.4 ML. This indicates the graphene decomposed and C atoms diffused into the Cu substrate. It was also found from SIMS measurement that the amount of diffused C atoms in the thermal CVD process is smaller than that after vacuum annealing. These results suggest that the C atom diffusion into the Cu occurs frequently, but the diffused C atoms do not contribute to the graphene growth on the Cu surface.