Coherent excitation of the optic phonon in Si: Transiently stimulated Raman scattering with a finite-lifetime electronic excitation
Coherent excitation of the optic phonon in Si: Transiently stimulated Raman scattering with a finite-lifetime electronic excitation
复制标题
DOI：
10.1103/physrevb.76.085207
复制
发表时间：
2007-08
影响因子：
3.7
通讯作者：
D. M. Riffe;A. Sabbah
中科院分区：
文献类型：
--
作者：
D. M. Riffe;A. Sabbah
使用$28\text{\ensuremath{-}}\mathrm{fs}$, $800\text{\ensuremath{-}}\mathrm{nm}$激光脉冲，我们相干激发并随后探测具有时间相关反射率的Si区中心光学声子。声子诱导的反射率变化$\mathrm{\ensuremath{\Delta}}R∕R$很好地描述了一个欠阻尼振荡器的响应：$\mathrm{\ensuremath{\Delta}}R∕R\ensuremath{\propto}\phantom{\rule{0.2em}{0ex}}\mathrm{exp}(\ensuremath{-}t∕{\ensuremath{\tau}}_{ph})\phantom{\rule{0.2em}{0ex}}\mathrm{cos}(2\ensuremath{\pi}t∕{T}_{ph}+\ensuremath{\phi})$。测量相位$\ensuremath{\phi}$表明瞬态受激拉曼散射（TSRS）是相干声子产生的原因：我们的结果与最近不透明材料的TSRS理论很好地一致。E. Stevens等人，物理学。当我们将理论扩展到包括与振荡耦合的激发电荷密度的有限寿命时，Rev. B 65, 144304（2002）。我们还根据这一扩展理论讨论了以前在Te、Bi、Sb、Si和Ge上的实验结果。此外，我们测量的Si相干振荡周期${T}_{ph}$和衰减时间${\ensuremath{\tau}}_{ph}$与载流子密度相关的拉曼散射测量结果一致。
Using $28\text{\ensuremath{-}}\mathrm{fs}$, $800\text{\ensuremath{-}}\mathrm{nm}$ laser pulses we have coherently excited and subsequently probed, with time-dependent reflectivity, the Si zone-center optic phonon. The phonon-induced reflectivity change $\mathrm{\ensuremath{\Delta}}R∕R$ is well described by the response of an underdamped oscillator: $\mathrm{\ensuremath{\Delta}}R∕R\ensuremath{\propto}\phantom{\rule{0.2em}{0ex}}\mathrm{exp}(\ensuremath{-}t∕{\ensuremath{\tau}}_{ph})\phantom{\rule{0.2em}{0ex}}\mathrm{cos}(2\ensuremath{\pi}t∕{T}_{ph}+\ensuremath{\phi})$. The measured phase $\ensuremath{\phi}$ indicates that transiently stimulated Raman scattering (TSRS) is responsible for the coherent-phonon generation: our results are in good agreement with a recent theory of TSRS for opaque materials [T. E. Stevens et al., Phys. Rev. B 65, 144304 (2002)] when we extend the theory to include the finite lifetime of the excited charge density that couples to the oscillation. We also discuss previous experimental results on Te, Bi, Sb, Si, and Ge in light of this extended theory. Additionally, our measured period ${T}_{ph}$ and decay time ${\ensuremath{\tau}}_{ph}$ of the Si coherent oscillation are consistent with carrier-density-dependent Raman-scattering measurements.