Type-II multiple quantum well superlattices based on InAs/AlAsSb are investigated for ground- and excited-state charge carrier transport and excited-state charge carrier dynamics. It is found that ground-state transport matches well to impurity and optical phonon interactions, while the excited-state transport shows increased terahertz photoconductivity for the correct excitation conditions that have previously been linked to a metastability in the early time response after photoexcitation. This regime also shows a reduction in carrier mobility, which is also expected to be due to ambipolar diffusion and increased carrier–carrier scattering. Overall, carrier excited-state dynamics confirm the metastability in early time response and are related to strong Auger scattering. For increased excitation intensities, the Auger-scattering rate increases to obtain a lower carrier density more rapidly. The result is a stronger scattering of carriers energetically deeper into their respective bands, where they exhibit a much slower carrier recombination rate and can maintain their relative temperature as a result of a phonon bottleneck that forces reabsorption of optical phonons. In addition to a previously reported phonon bottleneck, the carrier dynamics offer potential pathways to stabilize hot carriers with further bandgap engineering.

中文翻译：

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用于光伏应用的 III-V 异质结构中的热载流子动力学和传输

研究了基于 InAs/AlAsSb 的 II 型多量子阱超晶格的基态和激发态电荷载流子传输以及激发态电荷载流子动力学。发现基态输运与杂质和光学声子相互作用很好地匹配，而激发态输运在正确的激发条件下显示出增加的太赫兹光电导率，而正确的激发条件以前与光激发后早期响应中的亚稳态有关。该方案还显示载流子迁移率降低，这也预计是由于双极扩散和载流子 - 载流子散射增加。总体而言，载流子激发态动力学证实了早期响应中的亚稳态，并且与强俄歇散射有关。为了增加激发强度，俄歇散射率增加以更快地获得较低的载流子密度。结果是载流子在能量上更深地散射到它们各自的带中，在那里它们表现出更慢的载流子复合率，并且由于声子瓶颈迫使光学声子重新吸收，它们可以保持它们的相对温度。除了先前报道的声子瓶颈之外，载流子动力学还提供了通过进一步的带隙工程来稳定热载流子的潜在途径。