Control of resonant electron capture in semiconductor quantum structures

用稳态光致发光和时间分辨光致发光系统研究了AlGaAs/GaAsQW结构中的共振载流子俘获。提出了一种具有AlAs隧道势垒的量子阱结构，以增强其共振效应。结果表明，共振电子俘获提高了电子捕获效率，缩短了电子捕获时间。研究还发现，在量子阱异质界面处插入隧道势垒会导致共振增强。在有效质量近似的基础上，我们证明了共振载流子俘获的光学类比，它很好地解释了实验结果。重要的是，共振电子俘获有望在低维量子结构中更加突出，如量子井线和量子井盒。从这个意义上说，目前的工作将为未来的工作奠定基础，以期在这些复杂的量子结构中实现载流子捕获。我们认为，共振电子捕获的控制将被视为一个关键问题，以便我们能够在这样的低维结构中定制载流子收集效率。

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.