▎ 摘　　要

Graphene is expected to be one of the most promising materials for nanoelectronics and spintronics. In most graphene-based devices, the graphene channel is placed on insulating substrates. Therefore, the study of interfacial interactions between graphene and the insulator surface is of critical importance. In this study, the vertical arrangement of graphene which is transferred on alpha-Al2O3(0001) has been studied by normal incidence X-ray standing wave (NIXSW) technique. The analysis of the NIXSW profile reveals that the graphene layer is located at 3.57 angstrom above the alpha-Al2O3(0001) surface, which is larger than the interlayer distance of graphite (3.356 angstrom). Micro Raman spectroscopy shows that the transferred graphene has a limited spatial distribution of hole concentration. The present study shows that transferred graphene on the sapphire substrate followed by vacuum-annealing has an atomically flat surface free from residual contaminations such as organic compounds and there occurs the hole-doping in graphene.