Theoretical and experimental study of the optical absorption at longitudinal phonon or phonon-plasmon coupling mode energy: An example of GaN
Theoretical and experimental study of the optical absorption at longitudinal phonon or phonon-plasmon coupling mode energy: An example of GaN
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DOI：
10.1063/1.4754555
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发表时间：
2012-09
影响因子：
3.2
通讯作者：
Y. Ishitani
中科院分区：
文献类型：
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作者：
Y. Ishitani
Berreman已经报道了p偏振红外光在纵向光学（LO）声子能量处的反射率损失。从界面极化电荷对电偶极矩的吸收和界面极化激元的传播两个方面讨论了这种损耗的来源。然而，吸收效应的存在并不清楚。在本课题中，我们以具有大极化电荷的GaN薄膜为例，通过理论和实验分析区分这两种效应对光谱的影响。它是发现的第一次，由电偶极子在谐振能量与LO声子或LO声子-等离子体激元耦合（LOPC）模式的吸收被确定为独立的界面极化激元效应，通过改变波数分量平行于界面的衰减全反射分析。我们构造了薄膜在LO声子或LOPC模能量附近的赝介电函数的理论表达式，并给出了薄膜的赝介电函数的定量表达式。
Reflectance loss of p-polarized infrared light at longitudinal optical (LO) phonon energies has been reported by Berreman. The origin of this loss has been discussed in view of the absorption by electric dipole moment by the polarization charges at the interfaces and propagation of interface polaritons. However, the existence of the absorption effect is not clear. In this issue, we take an example of GaN films with large polarization charges, and distinguish the two effects on optical spectra by theoretical and experimental analysis. It is found for the first time that the absorption by electric dipoles at the resonant energy with the LO phonon or LO phonon-plasmon coupling (LOPC) mode is identified separately from the interface polariton effect by varying the wavenumber component parallel to the interfaces by attenuated total reflectance analysis. We construct a theoretical expression of the pseudo-dielectric function of thin films around the LO phonon or LOPC mode energies, and show the quantitative pro...