Control of resonant electron capture in semiconductor quantum structures

利用稳态光致发光和时间分辨光致发光研究了AlGaAs/GaAs量子阱结构中载流子的共振俘获。为了提高量子阱的谐振效应，提出了一种新的AlAs隧道势垒量子阱结构。已经清楚地表明，由于共振电子捕获，电子捕获效率增加并且电子捕获时间减少。研究还发现，在量子阱异质界面处插入隧道势垒会显著地导致共振增强。我们在有效质量近似的基础上，用电子波反射率的概念，证明了共振载流子俘获的光学类比，这很好地解释了实验结果.重要的是，共振电子俘获在低维量子结构如量子阱线和量子阱盒中将更加突出.从这个意义上说，目前的工作将是未来工作的基石，试图阐明这些复杂的量子结构中的载流子捕获。我们相信，控制共振电子捕获将被视为一个关键问题，以便我们可以定制在这种低维结构的载流子收集效率。

The resonant carrier capture in AlGaAs/GaAs QW structures was systematically investigated by both steady-state and time-resolved photoluminescence. The new structure of QWs with AlAs tunnel barriers was proposed to enhance the resonant effect. It has been clearly revealed that the electron capture efficiency is increased and the electron capture time is decreased due to the resonant electron capture. It has been also found that the insertion of tunnel barriers at QW heterointerfaces drastically leads to resonance enhancement. We demonstrate an optical analogy of the resonant carrier capture, in terms of electron wave reflectivity, on the basis of the effective mass approximation, which well explains the experimental results.Importantly, the resonant electron capture is expected to be more prominent in low-dimensional quantum structures such as quantum well wires and quantum well boxes. In this sense, the present work will be a cornerstone for future work rying to shed lights on carrier capture in these sophisticated quantum structures. We believe that the control of the resonant electron capture will be regarded as a key issue so that we can tailor the carrier collection efficiency in such low-dimensional structures.