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

• Applicant: Professorin Dr. Kerstin Volz
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2008 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 88737021

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.

• DFG Programme: Research Grants