Hole spin relaxation and intervalley electron scattering in germanium
Hole spin relaxation and intervalley electron scattering in germanium
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DOI：
10.1103/physrevb.84.214307
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发表时间：
2011-12-28
影响因子：
3.7
通讯作者：
Smirl, Arthur L.
中科院分区：
文献类型：
--
作者：
Loren, Eric J.;Rioux, J.;Smirl, Arthur L.
空穴自旋弛豫和谷间电子散射体锗在300 K的区别和选择性地研究使用光谱，时间和偏振分辨泵浦-探测差分传输技术，利用间接带隙性质的Ge和不同的圆形选择规则的直接分裂和重空穴价导带跃迁。自旋极化载流子通过圆极化泵浦注入到直接带隙中。随后，圆二色性与直接跨间隙带间跃迁从分裂和重空穴价带测量的探针脉冲调谐到询问这两个过渡。我们表明，保利阻塞的导电状态所需的直接过渡从分裂的价带由电子主导的二向色性的差分传输的早期，但一旦电子散射到侧谷，二向色性反转的符号，是由空穴阻塞的初始价态所需的直接heave空穴过渡，从而，使我们能够研究空穴动力学。从这些测量，我们估计的谷间散射时间类似于200 fs和有效的空穴自旋弛豫时间类似于700 fs。
Hole spin relaxation and intervalley electron scattering in bulk Ge at 300 K are distinguished and selectively investigated using a spectrally, temporally, and polarization-resolved pump-probe differential transmission technique that takes advantage of the indirect band gap nature of Ge and of the differing circular selection rules for the direct split-off and heavy-hole valence-to-conduction band transitions. Spin-polarized carriers are injected across the direct gap by a circularly polarized pump. Subsequently, the circular dichroisms associated with direct across-gap interband transitions from the split-off and heavy-hole valence bands are measured by a probe pulse tuned to interrogate both transitions. We demonstrate that the Pauli-blocking of the conduction states needed for the direct transition from the split-off valence band by electrons dominate the dichroism in the differential transmission for early times, but once the electrons scatter to the side valleys, the dichroism reverses sign and is caused by the holes blocking the initial valence states needed for the direct heave-hole transition, thus, allowing us to study the hole dynamics. From these measurements, we estimate an intervalley scattering time of similar to 200 fs and an effective hole spin relaxation time of similar to 700 fs.