A review on SEM imaging of graphene layers

Atomic-thick graphene has stimulated great interests for exploring fundamental science and technological applications due to its promising electronic, mechanical and thermal properties. It is important to gain a deeper understanding of geometrical/structural characteristics of graphene and its properties/performance. Scanning electron microscopy (SEM) is indispensable for characterizing graphene layers. This review details SEM imaging of graphene layer, including the SEM image contrast mechanism of graphene layers, imaging parameter-dependent contrast of graphene layers and the influence of polycrystalline substrates on image contrast. Furthermore, a summary of SEM applications in imaging graphene layers is also provided, including layer-number determinations, study of chemical vapor deposition (CVD)-growth mechanism, and reveal of anti-corrosive failure mechanism of graphene layers. This review will provide a systematic and comprehensive understanding on SEM imaging of graphene layers for graphene community.