Graphene growth and carbon diffusion process during vacuum heating on Cu(111)/AlO substrates

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

In this study, behavior of carbon atoms in annealing/cooling process of graphene/Cu(111) substrates is investigated using photoelectron spectroscopy and secondary ion mass spectrometry. After growth of graphene on Cu(111) surfaces, CuO was formed at the graphene/Cu interface during transportation through the atmosphere. The CuO layer completely disappeared by vacuum annealing at 773 K. Graphene was decomposed and carbon atoms diffuse into the Cu substrate by elevation of temperature up to 1223 K. When the sample was cooled down, the carbon atoms did not segregate on the surface and remain in the Cu substrate. This result indicates the carbon atoms easily diffuse into Cu substrates in vacuum annealing while the amount of diffused carbon atoms in the chemical vapor deposition (CVD) process is smaller, suggesting that the barrier layer which prevents from the diffusion of C atoms exists on Cu surfaces at the graphene CVD growth.