Lei Ren, Qi Zhang, Jun Yao, Zhengzong Sun, Ryosuke Kaneko, Zheng Yan, Sebastien L. Nanot, Zhong Jin, Iwao Kawayama, Masayoshi Tonouchi, James M. Tour, Junichiro Kono
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 (10-10000 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.
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http://arxiv.org/abs/1204.4774
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