Gate-tuning of graphene plasmons revealed by infrared nano-imaging
Gate-tuning of graphene plasmons revealed by infrared nano-imaging
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DOI：
10.1038/nature11253
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发表时间：
2012-07-05
期刊：
影响因子：
64.8
通讯作者：
Basov, D. N.
中科院分区：
文献类型：
--
作者：
Fei, Z.;Rodin, A. S.;Basov, D. N.
表面等离子体是金属或半导体中电子的集体振荡，能够在亚波长尺度(1-5)限制和控制电磁能量。等离子体激元的快速发展在很大程度上依赖于器件纳米制造的进步(5-7)，而对等离子体介质的可调谐特性的关注较少。一种这样的介质-石墨烯-可以通过改变施加的电压(8-11)来方便地调节其电子和光学性质。在这里，利用红外纳米成像，我们证明了常见的石墨烯/二氧化硅/硅背栅结构支持表面等离子体的传播。在技术上相关的红外频率下，石墨烯等离子体的波长约为200纳米，它们可以传播几倍于此距离。通过改变栅极电压，我们成功地改变了这些等离子激元的幅度和波长。利用等离子体激元干涉术，我们研究了石墨烯中的损耗，方法是探索在我们的纳米探针尖端和样品边缘之间形成的等离子体激元驻波的真实空间轮廓。通过这一分析量化的等离子体耗散与石墨烯的奇异电动力学有关(10)。我们的可调谐石墨烯装置的标准等离子体优值系数超过了普通的金属结构。
Surface plasmons are collective oscillations of electrons in metals or semiconductors that enable confinement and control of electromagnetic energy at subwavelength scales(1-5). Rapid progress in plasmonics has largely relied on advances in device nano-fabrication(5-7), whereas less attention has been paid to the tunable properties of plasmonic media. One such medium-graphene-is amenable to convenient tuning of its electronic and optical properties by varying the applied voltage(8-11). Here, using infrared nano-imaging, we show that common graphene/SiO2/Si back-gated structures support propagating surface plasmons. The wavelength of graphene plasmons is of the order of 200 nanometres at technologically relevant infrared frequencies, and they can propagate several times this distance. We have succeeded in altering both the amplitude and the wavelength of these plasmons by varying the gate voltage. Using plasmon interferometry, we investigated losses in graphene by exploring real-space profiles of plasmon standing waves formed between the tip of our nano-probe and the edges of the samples. Plasmon dissipation quantified through this analysis is linked to the exotic electrodynamics of graphene(10). Standard plasmonic figures of merit of our tunable graphene devices surpass those of common metal-based structures.