▎ 摘　　要

Optical antennas are devices that efficiently convert the energy of free propagating radiation into localized energy and vice versa. The development of optical antennas can improve the efficiency of sensing, photodetection, light emission, and spectroscopy. Graphene rings are a promising material for advanced optical antennas because their plasmons are more electromagnetically confined than metallic plasmons. In this report, we describe the growth of embedded and protrusive graphene rings by annealing Si-terminated 6H-SiC under Ar gas. We found that the growth of the graphene rings depends on both the annealing temperature and the ambient Ar pressure. A bottom-up fabrication method can preserve intact ring edges unlike electron-beam lithographic methods. Moreover, the growth of protrusive graphene rings without bonding between the ring edge and the SiC substrate is emphasized because the ring edge structures are similar to those of free-standing graphene rings, and this provides a new option for graphene applications on Si-terminated SiC. Copyright (c) 2014 John Wiley & Sons, Ltd.