Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK.
Nat Commun. 2012;3:1228. doi: 10.1038/ncomms2235.
Graphene is a single layer of covalently bonded carbon atoms, which was discovered only 8 years ago and yet has already attracted intense research and commercial interest. Initial research focused on its remarkable electronic properties, such as the observation of massless Dirac fermions and the half-integer quantum Hall effect. Now graphene is finding application in touch-screen displays, as channels in high-frequency transistors and in graphene-based integrated circuits. The potential for using the unique properties of graphene in terahertz-frequency electronics is particularly exciting; however, initial experiments probing the terahertz-frequency response of graphene are only just emerging. Here we show that the photoconductivity of graphene at terahertz frequencies is dramatically altered by the adsorption of atmospheric gases, such as nitrogen and oxygen. Furthermore, we observe the signature of terahertz stimulated emission from gas-adsorbed graphene. Our findings highlight the importance of environmental conditions on the design and fabrication of high-speed, graphene-based devices.
石墨烯是由碳原子通过共价键连接而成的单层结构，它仅在 8 年前被发现，但已经引起了广泛的研究和商业关注。最初的研究集中在其显著的电子特性上，例如观测到无质量的狄拉克费米子和半整数量子霍尔效应。现在，石墨烯正在触摸屏显示器、高频晶体管的沟道以及基于石墨烯的集成电路中得到应用。利用石墨烯在太赫兹频率电子学中的独特性质具有很大的潜力；然而，目前仅刚开始出现初步实验来探测石墨烯在太赫兹频率下的响应。在这里，我们表明，大气气体（如氮气和氧气）的吸附会显著改变石墨烯在太赫兹频率下的光电导率。此外，我们还观察到了来自吸附气体的石墨烯的太赫兹受激发射的特征。我们的研究结果强调了环境条件对高速、基于石墨烯的器件设计和制造的重要性。
