Strong phonon-plasmon coupled modes in the graphene/silicon carbide heterosystem
Strong phonon-plasmon coupled modes in the graphene/silicon carbide heterosystem
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DOI：
10.1103/physrevb.82.201413
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发表时间：
2010-11-24
影响因子：
3.7
通讯作者：
Schaefer, J. A.
中科院分区：
文献类型：
--
作者：
Koch, R. J.;Seyller, Th.;Schaefer, J. A.
我们报告了石墨烯中的电荷载流子等离子体激元Ω（PL）与底层SiC（0001）衬底的表面光学声子Ω（SO）在长波长极限（q（平行于）-> 0）下的强耦合，其中SiC（0001）衬底具有低电子浓度（n=1.2x10（15）cm（-3））。依赖于能量的能量损失谱给出了两个耦合的声子-等离子体振子模式omega（+/-）的明确证据，该耦合的声子-等离子体振子模式omega（+/-）由omega（SO）（q（平行于）-> 0）和omega（TO）（q（平行于）>> 0）之间的间隙分开，特别是对于较高的初级电子能量（E-0 >= 20 eV）的横向光学声子模式。基于介电理论的简化模型能够模拟我们的能量损失谱以及两个耦合声子-等离子体振子模式ω（+/-）的色散。相反，Liu和Willis [Phys. Rev. B 81，081406（R）（2010）]在他们最近的出版物中根据他们的能量损失数据假设没有间隙和具有单峰结构的不连续色散曲线。
We report on strong coupling of the charge-carrier plasmon omega(PL) in graphene with the surface-optical phonon omega(SO) of the underlying SiC(0001) substrate with low-electron concentration (n=1.2x10(15) cm(-3)) in the long-wavelength limit (q(parallel to)-> 0). Energy-dependent energy-loss spectra give clear evidence of two coupled phonon-plasmon modes omega(+/-) separated by a gap between omega(SO)(q(parallel to)-> 0) and omega(TO)(q(parallel to)>> 0), the transverse-optical-phonon mode, in particular, for higher primary electron energies (E-0 >= 20 eV). A simplified model based on dielectric theory is able to simulate our energy-loss spectra as well as the dispersion of the two coupled phonon-plasmon modes omega(+/-). In contrast, Liu and Willis [Phys. Rev. B 81, 081406(R) (2010)] postulate in their recent publication no gap and a discontinuous dispersion curve with a one-peak structure from their energy-loss data.