Termination of graphene edges created by hydrogen and deuterium plasmas

Edge engineering is important for both fundamental research and applications as the device size decreases to nanometer scale. This is especially the case for graphene because a graphene edge shows totally different electronic properties depending on the atomic structure and the termination. It has recently been shown that an atomically precise zigzag edge can be obtained by etching graphene and graphite using hydrogen (H) plasma. However, edge termination had not been studied directly. In this study, termination of edges created by H-plasma is studied by high-resolution electron energy loss spectroscopy to show that the edge is sp2 bonded and the edge carbon atom is terminated by only one H atom. This suggests that an ideal zigzag edge, which is not only atomically precise but also sp2 bonding, can be obtained by H-plasma etching. Etching of the graphite surface with plasma of a different isotope, deuterium (D), is also studied by scanning tunneling microscopy to show that D-plasma anisotropically etches graphite less efficiently, although it can make defects more efficiently, than H-plasma.

Automated summary

Edge engineering is crucial for both fundamental research and applications, especially in the case of graphene, where the electronic properties of the edge depend on the atomic structure and termination. This study investigates the termination of edges created by hydrogen (H) plasma etching, revealing that the edge is sp2 bonded with only one H atom terminating the edge carbon atom. The results suggest that an ideal atomically precise and sp2 bonded zigzag edge can be achieved through H-plasma etching. Additionally, scanning tunneling microscopy studies show that deuterium (D) plasma anisotropically etches graphite less efficiently but can create defects more efficiently than H-plasma.