In situ observation of graphene formation on polycrystalline Cu substrate

As a stable 2-dimensional? material, graphene has been extensively studied. Currently, most of explanations on growth mechanisms are based on the experimental results after graphene formation, and the direct observation on the whole growth process is still lacking. To produce single-crystal graphene as large as possible and finally control its growth, the deep understanding on the growth mechanisms is indispensable. By in situ technique, it is possible to observe the whole process including the morphology change of the substrate surface, formation of graphene crystal and so on during growth. In situ scanning tunneling microscopy (STM) analyses have showed this process at atomic scale [1]. Complementary to in situ STM, in situ scanning electron microscopy (SEM) observation provides a larger field of view, which may help us to better understand the growth mechanisms [2]. In this study, the whole graphene growth process on polycrystalline Cu substrate is observed by in situ SEM. The morphology changes of Cu surface and graphene structures formed under various conditions are carefully investigated. The influences of experimental parameters including temperature and growth time on the layer number o