Auger-recomination in self-assembled quantum dots

俄歇效应是一种多粒子散射效应，在材料分析(俄歇光谱)和光电设备中具有重要意义，在这些设备中，纳米颗粒被用作光发射器，就像商业电视屏幕中的荧光介质一样。在这种胶体纳米粒子中，俄歇过程对光子转换过程中的低效起决定性作用，因为能量是以非辐射的方式耗散的。这会导致纳米颗粒的光谱漂移(发射波长的变化)和闪烁(发光的开关)。在单个自组织量子点中，俄歇效应一直被忽略。在本项目中，我们将对这种俄歇效应进行详细的研究，以便更深入地理解这种对自组装量子点模型系统的基本效应。为此，将生长各种量子点结构，用一系列方法对其进行表征，最后通过共振荧光研究它们的俄歇特性。这项工作将在位于波鸿鲁尔大学和杜伊斯堡-埃森大学的两位项目负责人的密切合作下完成。特别是具有不同大小和形状的量子点，具有不同的隧道耦合到电荷库和额外的超晶格以产生亚带态的样品结构将被生长并通过共振荧光进行测量。此外，还将研究外加磁场和内电场对俄歇复合速率的影响。对自组织量子点中俄歇效应的详细理解可以揭示抑制俄歇复合的外部或内部调谐旋钮，并创造出具有高强度和窄线宽的量子光发射器结构。

The Auger-effect is a many-particle scattering effect and of great significance, for instance, in material analysis (Auger-spectroscopy) and in optoelectronic devices where nanoparticles are used as light emitters like the fluorescence medium in commercially available television screens. In such colloidal nanoparticles, the Auger-process is decisive for inefficiencies in the photon conversion process, as the energy gets dissipated non-radiatively. This leads to spectral wandering (shifts of the emission wavelength) and blinking (on- and off-switching of the luminescence) of the nanoparticles. In single self-organized quantum dots, the Auger-effect has been neglected so far. In the presented project, this Auger-effect will be studied in detail in order to a get a deeper understanding of this fundamental effect on a well-known model system of self-assembled quantum dots. For this purpose, various quantum dot structures will be grown, characterized by a range of methods and finally investigated via resonance fluorescence towards their Auger-characteristics. This will be done in close cooperation of two project leaders located at the Ruhr-Universität Bochum and the Universität Duisburg-Essen. Especially sample structures with quantum dots of different size and shape, having different tunnel-coupling to a charge reservoir and an additional super lattice for creation of sub-band states will be grown and measured by resonance fluorescence. Moreover, the influence of external magnetic- and internal electric field on the Auger-recombination rate will be studied. A detailed understanding of the Auger effect in self-organized quantum dots could reveal external or internal tuning knobs to suppress the Auger-recombination and create structures for quantum-light emitters with high intensity and narrow linewidth.