Damping mechanism of terahertz plasmons in graphene on heavily doped substrate
Damping mechanism of terahertz plasmons in graphene on heavily doped substrate
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DOI：
10.1063/1.4867971
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发表时间：
2014-03-14
影响因子：
3.2
通讯作者：
Otsuji, T.
中科院分区：
文献类型：
--
作者：
Satou, A.;Koseki, Y.;Otsuji, T.
从理论上研究了太赫兹频率下石墨烯中等离子体激元与重掺杂衬底中表面等离子体激元的耦合。我们发现，一个巨大的散射率可以完全阻尼的等离子体激元，因此，适当的材料和几何参数的选择是必不可少的，以抑制耦合效应，并获得最小的阻尼率在石墨烯。即使掺杂浓度为10（19）- 10（20）cm（-3），石墨烯和衬底之间的介电层厚度为100 nm，这是具有重掺杂衬底的真实的石墨烯样品中的典型值，与声学声子限制的阻尼率相比，阻尼率的增加也不可忽略。研究了阻尼率与波数、石墨烯与衬底和栅极与石墨烯间隔的厚度、衬底掺杂浓度和周围材料的介电常数的关系。结果表明，阻尼率可以大大降低的栅极屏蔽，这抑制了石墨烯等离子体激元到衬底中的场扩展。(C)2014 AIP Publishing LLC.
Coupling of plasmons in graphene at terahertz frequencies with surface plasmons in a heavily doped substrate is studied theoretically. We reveal that a huge scattering rate may completely damp out the plasmons, so that proper choices of material and geometrical parameters are essential to suppress the coupling effect and to obtain the minimum damping rate in graphene. Even with the doping concentration 10(19) - 10(20) cm(-3) and the thickness of the dielectric layer between graphene and the substrate 100nm, which are typical values in real graphene samples with a heavily doped substrate, the increase in the damping rate is not negligible in comparison with the acoustic-phonon-limited damping rate. Dependence of the damping rate on wavenumber, thicknesses of graphene-to-substrate and gate-to-graphene separation, substrate doping concentration, and dielectric constants of surrounding materials are investigated. It is shown that the damping rate can be much reduced by the gate screening, which suppresses the field spread of the graphene plasmons into the substrate. (C) 2014 AIP Publishing LLC.