Cooling dynamics of photoexcited carriers in Si studied using optical pump and terahertz probe spectroscopy
Cooling dynamics of photoexcited carriers in Si studied using optical pump and terahertz probe spectroscopy
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DOI：
10.1103/physrevb.83.085207
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发表时间：
2011-01
影响因子：
3.7
通讯作者：
Takeshi Suzuki;R. Shimano
中科院分区：
文献类型：
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作者：
Takeshi Suzuki;R. Shimano
我们研究了光激发载流子在Si中的动力学，通过使用光泵和太赫兹探测光谱在2和25毫电子伏之间的能量范围。激子的形成动力学从未绑定的$e$-$h$对的研究通过激子在12兆电子伏（3太赫兹）的1$s$-2$p$跃迁的出现。通过考虑载流子与声学声子和光学声子的带间和带内散射，揭示了低温晶格系统中光注入热载流子（电子和空穴）的热化机制.在声子散射过程微观分析的基础上，数值计算了电子和空穴的整体冷却速率，结果很好地解释了实验观察到的载流子冷却动力学。光激载流子的热化过程合理地解释了带隙以上光激发后硅中激子的长形成时间。
We investigated the photoexcited carrier dynamics in Si by using optical pump and terahertz probe spectroscopy in an energy range between 2 and 25 meV. The formation dynamics of excitons from unbound $e$-$h$ pairs was studied through the emergence of the 1$s$-2$p$ transition of excitons at 12 meV (3 THz). We revealed the thermalization mechanism of the photoinjected hot carriers (electrons and holes) in the low-temperature lattice system by taking account of the interband and intraband scattering of carriers with acoustic and optical phonons. The overall cooling rate of electrons and holes was numerically calculated on the basis of a microscopic analysis of the phonon scattering processes, and the results well account for the experimentally observed carrier cooling dynamics. The long formation time of excitons in Si after the above-gap photoexcitation is reasonably accounted for by the thermalization process of photoexcited carriers.