Coherent phonon modes of crystalline and amorphous Ge2Sb2Te5 thin films: A fingerprint of structure and bonding
Coherent phonon modes of crystalline and amorphous Ge2Sb2Te5 thin films: A fingerprint of structure and bonding
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晶体和非晶 Ge2Sb2Te5 薄膜的相干声子模式：结构和键合的指纹
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
R. Hicken
中科院分区：
文献类型：
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作者：
A. Shalini;Y. Liu;F. Katmis;W. Braun;G. P. Srivastava;R. Hicken
飞秒光泵浦-探测测量已在外延，多晶，非晶薄膜的Ge 2Sb 2 Te 5（GST）。在外延薄膜的时间分辨各向异性反射率（AR）测量中观察到频率为3.4 THz的主要相干光学声子模式，并根据其振幅和相位对泵浦和探测偏振的依赖性推断其具有3维T2类特征。相比之下，多晶相和非晶相在反射率（R）和AR测量中均表现出约4.5 THz频率的相对较弱模式。拉曼显微镜测量证实了在泵浦-探测测量中观察到的模式的存在，并揭示了额外的模式。虽然拉曼光谱是定性相似的所有三个阶段的GST，模式频率被发现是不同的实验误差范围内，从3.2至3.6太赫兹和4.3至4.7太赫兹，表明详细的晶体结构有显着影响的声子频率。
Femtosecond optical pump-probe measurements have been made upon epitaxial, polycrystalline, and amorphous thin films of Ge2Sb2Te5 (GST). A dominant coherent optical phonon mode of 3.4 THz frequency is observed in time-resolved anisotropic reflectance (AR) measurements of epitaxial films, and is inferred to have 3-dimensional T2-like character based upon the dependence of its amplitude and phase on pump and probe polarization. In contrast, the polycrystalline and amorphous phases exhibit a comparatively weak mode of about 4.5 THz frequency in both reflectivity (R) and AR measurements. Raman microscope measurements confirm the presence of the modes observed in pump-probe measurements, and reveal additional modes. While the Raman spectra are qualitatively similar for all three phases of GST, the mode frequencies are found to be different within experimental error, ranging from 3.2 to 3.6 THz and 4.3 to 4.7 THz, indicating that the detailed crystallographic structure has a significant effect upon the phonon f...
影响因子：
3.2
作者：
Liu, Y.;Aziz, M. M.;Hicken, R. J.
通讯作者：
Hicken, R. J.