Institute of Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
J Phys Condens Matter. 2012 May 9;24(18):185801. doi: 10.1088/0953-8984/24/18/185801. Epub 2012 Apr 5.
Time-resolved photoluminescence (PL) characteristics of type-II GaAsSb/GaAs quantum wells are presented. The PL kinetics are determined by the dynamic band bending effect and the distribution of localized centers below the quantum well band gap. The dynamic band bending results from the spatially separated electron and hole distribution functions evolving in time. It strongly depends on the optical pump power density and causes temporal renormalization of the quantum well ground-state energy occurring a few nanoseconds after the optical pulse excitation. Moreover, it alters the optical transition oscillator strength. The measured PL lifetime is 4.5 ns. We point out the critical role of the charge transfer processes between the quantum well and localized centers, which accelerate the quantum well photoluminescence decay at low temperature. However, at elevated temperatures the thermally activated back transfer process slows down the quantum well photoluminescence kinetics. A three-level rate equation model is proposed to explain these observations.
呈现了 II 型 GaAsSb/GaAs 量子阱的时间分辨光致发光（PL）特性。PL 动力学由动态能带弯曲效应和量子阱带隙以下的局域中心分布决定。动态能带弯曲是由在时间上演变的空间分离的电子和空穴分布函数引起的。它强烈依赖于光泵浦功率密度，并导致光脉冲激发后几纳秒内量子阱基态能量的时间重整化。此外，它改变了光学跃迁振子强度。测量的 PL 寿命为 4.5ns。我们指出了量子阱和局域中心之间电荷转移过程的关键作用，这加速了低温下量子阱的光致发光衰减。然而，在高温下，热激活的反向转移过程会减缓量子阱的光致发光动力学。提出了一个三能级速率方程模型来解释这些观察结果。
