Einfluss von Elementen mit kleinen kovalenten Radien auf die (Nano)Struktur von III/V Halbleitermaterialien

本应用研究了新型亚稳III/V半导体的生长和定量结构特征，这些半导体含有与基体原子的共价半径和电负性有很大不同的元素。技术相关材料的例子是Ga（NAsP）和（BGa）（AsP）以及Ga(NAsBi)，其中氮(N)和硼(B)明显小于其他合金元素，Bi（铋）明显大于其他合金元素。这些半导体材料对器件极其重要。稀氮化物和含b材料是直接在硅衬底上集成光电III/V材料的候选材料。稀铋在电信波长范围内具有巨大的潜力，可以最大限度地减少损耗，这限制了目前基于inp的激光器的应用。从基本观点来看，这些取代原子对局部键排列和局部电荷分布的影响的理解也是有趣的。除了局部晶格畸变外，我们还将阐明这些材料由于与这些元素合金化而经历的结构形成过程。由于B和N或Bi分别占据了III/V半导体各自的III族和V族亚晶格，因此我们还将理解生长对III族和V族物质的影响，而不是不一致蒸发的V族物质。通过金属有机气相外延可以生长出不同成分的晶体。不同的透射电镜技术将结合稳定晶体结构的理论描述以及电子衍射的理论建模来应用。这种详细的、基本的对量化结构特性的理解也将有助于优化器件性能。

The present application investigates the growth as well as the quantitative structural characteristics of novel metastable III/V semiconductors containing elements with covalent radii and electronegativity, which are highly different from the ones of the matrix atoms. Examples of technologically relevant materials are Ga(NAsP) and (BGa)(AsP) as well as Ga(NAsBi) where nitrogen (N) as well as boron (B) are significantly smaller than the rest of the alloying elements and Bi (bismuth) is significantly larger. These semiconductor materials are extremely important for devices. The dilute nitrides and B-containing materials are candidates in an integration scenario of optoelectronic III/V materials directly on silicon substrates. The dilute bismide has great potential for lasers in the telecommunication wavelength range, where it could minimize the losses, which limit the application of InP-based lasers today. The understanding of the influence of these substitutional atoms on the local bonding arrangement as well as on the local charge distribution is also interesting from fundamental point of view. Despite from the local lattice distortion, we will also clarify structure formation processes, which these materials undergo due to the alloying with these elements. A comprehension of the effects of growth determining group-III species in contrast to incongruently evaporating group-V species will also be established, as B and N or Bi, respectively, occupy positions in the respective group-III and group-V sublattice of the III/V semiconductor. Crystals having different compositions will be grown by metal organic vapour phase epitaxy. Different transmission electron microscopic techniques will be applied in combination with theoretical description of stable crystal structures as well as theoretical modelling of electron diffraction. This detailed, fundamental understanding of the quantified structural characteristics will also help to optimize device performance.