Transmission electron microscopy observation of suspended graphene at elevated temperature

Abstract

Graphene, after being first isolated in 2004, has received great scientific attention because of its distinctive two-dimensional band structure and unique physical and electronic properties. Graphene synthesis has been developed since mechanical exfoliation methods. After mechanical exfoliation, graphene was exfoliated by chemical methods and synthesized by the graphitization of SiC single-crystal surfaces. Then graphene was precipitated on transition metal surfaces. Recently, graphene was grown by chemical vapor deposition (CVD) on transition metal, and these CVD methods can be obtained high-quality and large-area graphene. In order to use the graphene in electronic applications and combine the graphene into industry actually, it is important to understand the properties and nature of graphene in various conditions. We report here the observation of suspended CVD growth graphene during heating condition using transmission electron microscopy. To minimize the electron beam damage on graphene, the multi-layer graphene used in this experiment. This observation reveals the crystallinity improvement of residue-free gra-phene during heating by self-repair of the lattice. Also, the graphene sheet containing metal residue (consid-ered as copper particles remained after CVD graphene copper etching) was ripped by electron-beam excited metal-catalyst reaction. The seriously ripped graphene due to metal-catalyst reaction and electron beam damage could not recover even though heated for self-healing. By the way, graphene nanopore within critical size filled by self-healing at elevated temperature to minimized free energy.