Characterization of HOPG, Sputtered HPOG and Graphene by ToF-SIMS and XPS

Extended Abstract Graphene, a single layer of graphite, has attracted much attention due to its physical properties and two-dimensional structure. It has been used in many important industrial applications, including batteries, electronic devices and sensors. The cleanliness of graphene surfaces is important for successful uses of graphene in these applications. Surfaces of highly oriented pyrolytic graphite (HOPG), which can be regarded as the surfaces of defect-free graphene and surfaces of graphene were characterized by two very powerful surface analysis techniques X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) [1-4]. XPS results indicated that the impurities on the surfaces of graphene and HOPG can be removed by annealing samples of graphene and HOPG in vacuum at 400 o C [5]. In addition, ToF-SIMS results showed that even a small amount of poly(methyl methacrylate) (PMMA) impurity on the graphene surface can be removed by annealing the sample in vacuum at 500 o C. In the C1s spectrum of clean HOPG, an asymmetric sp 2 carbon peak and a π-π* shake-up peak were present, indicating the absence of defects. An additional sp 3