Structures And Spectroscopies for Epitaxial Graphene With Metal Decoration
Y-J Chan1*, C-H Huang2, S-Y Wu1, T-H Wu1, P-Y Cheng3, D-H Wei3, C-B Wu4, V. Yeh5, C-C Kuo1
1Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
2Program for Synchrotron Radiation and Neutron Beam Applications, National Sun Yat-sen University, Kaohsiung, Taiwan
3National Synchrotron Radiation Research Center, Hsinchu, Taiwan
4Department of Physics, Chung Yuan Christian University, Taoyuan, Taiwan
5Department of Physics, National Dong Hwa University, Hualian, Taiwan
* presenting author:Yao-Jui Chan,
Metallic contact on graphene provides a new route to tailor the electronic properties of graphene. Tunable carrier types and gap width have been observed on graphene contacted with different metals. Much efforts has been devoted to the studies for the chemical vapor deposition growth graphene on the different metallic substrate. However, the studies for the metallic layer deposited on the graphene is still less discussed. Here, we focus on the variation of structure and electronic structure of graphene after the decoration of gold, copper and cobalt. To realize the influence of metallic layer on graphene, the structure and electronic properties are explored by the low energy electron diffraction (LEED) and carbon K-edge X-ray absorption spectroscopy (XAS), respectively. From LEED pattern, we found that the structural ordering of graphene is sensitive to the metallic element. The arc-feature of graphene disappear after the growth Au and Cu, but it is not the case in Co/graphene. The disappearance of arc feature suggests that structural ordering of graphene is destructed on those surface. Meanwhile, there is no dramatic deformation in carbon K-edge XAS except for the peak core exciton. The intensity of core exciton is strongly suppressed for the Au and Cu decorated graphene surface. The observation of destructions of core exciton and long range structure for graphene seem to take place simultaneously. It suggests that the core exciton is an indicator for the graphene structural ordering. The details of our observation will be discussed in the talk.

Keywords: graphene, structure, XAS