Graphene Terahertz Plasmons: A Combined Transmission Spectroscopy and Raman Microscopy Study

Paiella, Roberto/0000-0002-7183-6249; Swan, Anna/0000-0002-3978-7993WOS: 000408077800018Graphene provides a promising materials platform for fundamental studies and device applications in plasmonics. Here we investigate the excitation of THz plasmon polaritons in large-area graphene samples on standard oxidized silicon substrates, via diffractive coupling from an overlying periodic array of metallic nanoparticles. Pronounced plasmonic absorption features are measured, whose frequencies can be tuned across a large portion of the THz spectrum by varying the array period. At the same time, the ability to tune these resonances actively via electrostatic doping is found to be strongly limited by the presence of large carrier density variations across the sample area induced by the underlying SiO2, which are measured directly by Raman microscopy. These results highlight the importance of minimizing charge "puddles" in graphene plasmonic devices, e.g., through the use of more inert substrates, in order to take full advantage of their expected dynamic tunability for applications in THz optoelectronics.National Science FoundationNational Science Foundation (NSF) [DMR-1308659]; Royal Thai Government Fellowship; Turkey Ministry of Education Fellowship; Division of Materials ResearchNational Science Foundation (NSF)NSF - Directorate for Mathematical & Physical Sciences (MPS) [1411008] Funding Source: National Science FoundationThis work was supported by the National Science Foundation under Grant DMR-1308659. K.T. and H.D. acknowledge partial support by a Royal Thai Government Fellowship and by a Turkey Ministry of Education Fellowship, respectively