Femtosecond pump-probe reflectivity study of silicon carrier dynamics
Femtosecond pump-probe reflectivity study of silicon carrier dynamics
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DOI：
10.1103/physrevb.66.165217
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发表时间：
2002-10-15
影响因子：
3.7
通讯作者：
Riffe, DM
中科院分区：
文献类型：
--
作者：
Sabbah, AJ;Riffe, DM
我们使用800 nm， 28 fs脉冲，在（5.5+/-0.3）x10(18) cm（-3）的激发密度下，研究了具有泵浦探针反射率的原生氧化端Si（001）的超快光学响应。时间相关的反射率变化包括由各向异性状态填充引起的三阶响应相干瞬态变化和由受激自由载流子、状态填充和晶格加热引起的线性响应变化。从相干瞬态变化中提取出与动量松弛相关的时间常数32+/- 5fs。状态填充和自由载流子响应对载流子温度敏感，允许测量到260+/-30 fs的电子-声子能量弛豫时间。反射率信号恢复到其初始值在很大程度上受表面复合控制：对于天然氧化端部Si(001)，推断表面复合速度为（3+/-1）x10(4) cm s（-1）。
We have studied the ultrafast optical response of native-oxide terminated Si(001) with pump-probe reflectivity using 800 nm, 28 fs pulses at an excitation density of (5.5+/-0.3)x10(18) cm(-3). Time-dependent reflectivity changes comprise third-order-response coherent-transient variations arising from anisotropic state filling and linear-response variations arising from excited free carriers, state filling, and lattice heating. A time constant of 32+/-5 fs associated with momentum relaxation is extracted from the coherent-transient variations. The state-filling and free-carrier responses are sensitive to carrier temperature, allowing an electron-phonon energy relaxation time of 260+/-30 fs to be measured. The recovery of the reflectivity signal back towards its initial value is largely governed surface recombination: a surface recombination velocity of (3+/-1)x10(4) cm s(-1) is deduced for native-oxide terminated Si(001).