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态III/V半导体的生长和定量结构特征，其中包含具有共价半径和电负性的元素，这些元素与基质原子的元素非常不同。与技术相关的材料的例子有Ga(NASP)和(BGA)(ASP)以及Ga(NAsBi)，其中氮(N)和硼(B)比其他合金元素小得多，而铋(铋)大得多。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。稀双酰胺在通信波长范围内具有很大的激光潜力，可以将损耗降到最低，这限制了今天InP基激光器的应用。从基本面的角度来理解这些替代原子对局域成键排列以及局域电荷分布的影响也是很有趣的。除了局部晶格变形，我们还将阐明这些材料由于与这些元素的合金化而经历的结构形成过程。还将建立对决定生长的III族物种与不一致地蒸发V族物种的影响的理解，因为B和N或Bi分别在III/V半导体的III族和V族亚晶格中占据位置。采用金属有机气相外延方法生长不同组成的晶体。不同的透射电子显微镜技术将与稳定晶体结构的理论描述以及电子衍射的理论模型相结合。对量化的结构特征的这种详细的、基本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.