Observation of suppressed terahertz absorption in photoexcited graphene
Observation of suppressed terahertz absorption in photoexcited graphene
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DOI：
10.1063/1.4795858
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发表时间：
2013-03-18
影响因子：
4
通讯作者：
Gedik, N.
中科院分区：
文献类型：
--
作者：
Frenzel, A. J.;Lui, C. H.;Gedik, N.
当光被半导体吸收时，由于带内跃迁，光激发的电荷载流子增强了对远红外辐射的吸收。我们在单层石墨烯中观察到相反的行为，石墨烯是一种具有线性色散的零能隙半导体。通过使用时域太赫兹（THz）光谱结合光泵浦激发，我们观察到光激发石墨烯的太赫兹辐射的吸收减少。测得的微分电导率的光谱形状表现出非德鲁德行为。我们讨论了几种可能的机制，有助于观察到的低频非平衡光学响应的石墨烯。(C)2013年美国物理学会。[http：//dx.doi.org/10.1063/1.4795858]
When light is absorbed by a semiconductor, photoexcited charge carriers enhance the absorption of far-infrared radiation due to intraband transitions. We observe the opposite behavior in monolayer graphene, a zero-gap semiconductor with linear dispersion. By using time domain terahertz (THz) spectroscopy in conjunction with optical pump excitation, we observe a reduced absorption of THz radiation in photoexcited graphene. The measured spectral shape of the differential optical conductivity exhibits non-Drude behavior. We discuss several possible mechanisms that contribute to the observed low-frequency non-equilibrium optical response of graphene. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4795858]