Coherent confined LO phonons in 70Ge/74Ge isotope superlattices generated by ultrafast laser pulses
Coherent confined LO phonons in 70Ge/74Ge isotope superlattices generated by ultrafast laser pulses
复制标题
超快激光脉冲产生的 70Ge/74Ge 同位素超晶格中的相干受限 LO 声子
DOI：
10.1103/physrevb.63.161304
复制
发表时间：
2001
影响因子：
3.7
通讯作者：
E. Haller
中科院分区：
文献类型：
--
作者：
M. Nakajima;H. Harima;K. Morita;K. Itoh;K. Mizoguchi;E. Haller
在一种新的非极性半导体Ge/Ge同位素超晶格中，观察到了20 fs超短激光脉冲辐照下产生的高阶相干受限LO声子模。的声子振荡进行傅立叶变换，并与基于平面力常数模型和键极化率方法的理论计算进行比较。计算谱与傅里叶变换谱的比较清楚地表明，相干声子的振幅仅由原子位移的程度决定，并且只有拉曼活动的奇数阶模是可观测的。泵浦光偏振态变化时的谱图清楚地表明，非极性半导体Ge中相干声子的产生机制是受激拉曼散射。
Generation of high-order coherent confined LO phonon modes by 20-fs ultrashort laser pulse irradiation was observed in a new class of nonpolar semiconductors; Ge/Ge isotope superlattices. The phonon oscillations were Fourier transformed and compared with a theoretical calculation based on a planar force-constant model and a bond polarizability approach. The comparison between the calculated and Fourier transformed spectra shows clearly that the amplitudes of coherent phonons are determined solely by the degree of the atomic displacement and that only the Raman active odd-number-order modes are observable. The spectra taken with variety of polarization of pump beam show clearly that the generation mechanism of coherent phonons in nonpolar semiconductor like Ge is stimulated Raman scattering.