Atomic structure determination of the graphene/sapphire interface by normal incident X-ay standing wave spectroscopy

Entani, Shiro; Sorokin, B. P.*; Avramov, P.; Otomo, Manabu; Matsumoto, Yoshihiro; Narita, Ayumi; Hirao, Norie; Shimoyama, Iwao   ; Sekiguchi, Tetsuhiro  ; Naramoto, Hiroshi*; Sakai, Seiji

We have studied the vertical atomic structure of a single-layer graphene/a-AlO(0001) interface with element-sensitive normal incident X-ray standing wave spectroscopy. The vertical distance at the interface measures 0.26 nm. We consider that the small distance is caused by the strong interaction at the interface. An ab initio atomic and electronic structure calculation supports the existence of the strong interaction that originates from the electrostatic interaction between graphene -system and unsaturated electrons of surface oxygen layer rather than van der Waals interaction.