Abstract-Terahertz and Infrared Spectroscopy of Gated Large-Area Graphene

http://pubs.acs.org/doi/abs/10.1021/nl301496r

Lei Ren†, Qi Zhang†, Jun Yao#, Zhengzong Sun‡, Ryosuke Kaneko§, Zheng Yan‡, Sébastien Nanot†, Zhong Jin‡, Iwao Kawayama§, Masayoshi Tonouchi§, James M. Tour‡, and Junichiro Kono*†¶

^†Department of Electrical and Computer Engineering and^‡Department of Chemistry, Rice University, Houston, Texas 77005, United States

^§ Institute of Laser Engineering, Osaka University, Yamadaoka 2-6, Suita, Osaka 565-0871, Japan

Department of Computer Science, Department of Mechanical Engineering and Materials Science, and^¶Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States

^# Applied Physics Program through the Department of Bioengineering, Rice University, Houston, Texas 77005, United States

Nano Lett., Article ASAP

DOI: 10.1021/nl301496r

Publication Date (Web): June 4, 2012

Copyright © 2012 American Chemical Society

We have fabricated a centimeter-size single-layer graphene device with a gate electrode, which can modulate the transmission of terahertz and infrared waves. Using time-domain terahertz spectroscopy and Fourier-transform infrared spectroscopy in a wide frequency range (10–10 000 cm^–1), we measured the dynamic conductivity change induced by electrical gating and thermal annealing. Both methods were able to effectively tune the Fermi energy, E_F, which in turn modified the Drude-like intraband absorption in the terahertz as well as the “2E_F onset” for interband absorption in the mid-infrared. These results not only provide fundamental insight into the electromagnetic response of Dirac fermions in graphene but also demonstrate the key functionalities of large-area graphene devices that are desired for components in terahertz and infrared optoelectronics.