Growth modes and interfaces of InGaN nanostructures by planar and cross-sectional STM

该项目旨在详细了解生长模式和生长机制，这对于基于III族氮化物的量子结构的组装和质量非常重要。对于一个详细的结构表征在生长过程中的原位扫描隧道显微镜的研究将被用来实现有关该材料系统的生长模式，偏析效应，InGaN量子阱结构中的成分波动的起源，和量子点的成核，以及它们对生长参数的依赖性的信息。原位实验将补充非原位调查，使用掠入射X射线衍射和小角散射，透射电子显微镜，同步辐射的X射线衍射和散射，和非原位STM。这种分析工具的组合将使我们能够研究各种各样的结构参数及其分布，如表面形态，量子点的大小和形状，以及量子结构的横向和/或垂直排列的顺序。本项目的样本将由项目I-1中申请的增长资源提供。一方面，从该项目中进行的实验中获得的结果可用于了解生长，并与项目III-1密切合作，对生长参数的影响进行可靠的预测。另一方面，该项目的结果对于建立适合于项目I-1和I-2所需的量子点阵列的优化制造的生长参数至关重要。此外，结构参数的知识是必不可少的，这样的量子结构的电子和光学性质的理论描述。因此，目前拟议的项目可为项目III-2和III-3提供宝贵的投入参数。将与II-2密切合作解决表面掺杂剂覆盖对生长模式的影响问题。

This project aims at a detailed understanding of the growth modes and growth mechanisms which are important for the assembly and quality of group-III-nitride based quantum structures. For a detailed structural characterization in-situ scanning tunneling microscopy studies during growth will be used to achieve information regarding the growth modes of this material system, segregation effects, the origin of compositional fluctuations in InGaN quantum well structures, and the nucleation of quantum dots as well as their dependence on the growth parameters. The in-situ experiments will be complemented by ex-situ investigations using grazing incidence x-ray diffraction and small angle scattering, transmission electron microscopy, synchrotron radiation based x-ray diffraction and scattering, and ex-situ STM. This combination of analytical tools will allow us to study a wide variety of structural parameters and their distribution, like surface morphology, size and shape of quantum dots, and ordering of the lateral and/or vertical arrangement of quantum structures. Samples for this project will be provided by the growth resources applied for in project I-1. The results obtained from the experiments to be performed in this project may, on the one hand, be used to understand growth and enable reliable predictions on the impact of growth parameters in close cooperation with project III-1. On the other hand, the results of this project will be essential to establish growth parameters suitable for an optimized fabrication of quantum dot arrays as needed for projects I-1 and I-2. In addition, the knowledge of structural parameters is essential for a theoretical description of the electronic and optical properties of such quantum structures. Therefore the presently proposed project can provide valuable input parameters for the projects III-2 and III-3. The issue of the impact of surface dopant coverage on the growth mode will be addressed in close cooperation with II-2.