Biegańska Dąbrówka, Pieczarka Maciej, Ryczko Krzysztof, Kubisa Maciej, Klembt Sebastian, Höfling Sven, Schneider Christian, Syperek Marcin
Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Poland.
Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Lehrstuhl für Technische Physik, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
Sci Rep. 2025 May 24;15(1):18071. doi: 10.1038/s41598-025-97221-x.
We present an experimental study on optical properties and dynamics of direct and spatially and momentum indirect excitons in AlGaAs/AlAs quantum wells near the crossover between - and X-valley confined electron states. The time-integrated photoluminescence experiment at T=4.8 K revealed three simultaneously observed optical transitions resulting from (a) a direct exciton recombination, involving an electron and a hole states both located in the -valley in the quantum well layer, and (b) two spatially and momentum indirect excitons, comprising of the confined electron states in the X-valley in the AlAs barrier with different effective masses and quantum well holes in the -valley. This interpretation has been based on the optical pumping density-dependent, temperature-dependent and spatially-resolved photoluminescence measurements, which provided the characterization of the structure, crucial in potential system's applications. Additionally, the time-resolved photoluminescence experiments unveiled complex carrier relaxation dynamics in the investigated quantum well system, which is strongly governed by a non-radiative carrier recombination - the characteristics further critical in potential system's use. This solid state platform hosting both direct and indirect excitons in a highly tunable monolithic system can benefit and underline the operation principles of novel electronic and photonic devices.
我们展示了一项关于在Γ-和X-谷受限电子态交叉附近的AlGaAs/AlAs量子阱中直接激子以及空间和动量间接激子的光学性质和动力学的实验研究。在T = 4.8 K下的时间积分光致发光实验揭示了同时观察到的三个光学跃迁，它们分别源于：(a) 直接激子复合，涉及量子阱层中均位于Γ-谷的一个电子和一个空穴态；(b) 两个空间和动量间接激子，由AlAs势垒中具有不同有效质量的X-谷受限电子态和Γ-谷中的量子阱空穴组成。这种解释基于光泵浦密度依赖、温度依赖和空间分辨的光致发光测量，这些测量提供了对该结构的表征，这在潜在系统的应用中至关重要。此外，时间分辨光致发光实验揭示了所研究量子阱系统中复杂的载流子弛豫动力学，这强烈受非辐射载流子复合的支配——这一特性在潜在系统的应用中同样至关重要。这个在高度可调谐的单片系统中同时承载直接激子和间接激子的固态平台，能够为新型电子和光子器件的工作原理提供帮助并加以强调。
