Plasmon Control Driven by Spatial Carrier Density Modulation in Graphene

Self-assembled monolayers of organosilane formed at the interfaces between graphene and SiO2/Si substrates were used for selective-area modulation of the charge carrier density in graphene. The interfaces between regions with different charge carrier densities were found to act as gate-tunable plasmonic reflectors, and this therefore allowed for spatial control of the plasmons. We numerically calculated the influence of the charge carrier concentration on the plasmon dispersion in graphene and found that the reflection coefficient may be tuned between 0 and 1.