Institute for Photon Science and Synchrotron Radiation

lll-V Nanostructures Project

Growth and characterization of semiconductor nanostructures in III/V materials

The research of our group focuses on the growth and characterization of semiconductor nanostructures in III/V materials systems. Together with the Theory and Simulation group of the IPS and in collaboration with the Solid State Physics Group of the University of Siegen,  and the Epitaxy Group of the Paul-Drude Institut für Festkörperelektronik in Berlin we currently aim at the growth of self-catalyzed III/V nanowires and their characterization using X-ray scattering methods, especially in-situ.

Employing X-ray scattering techniques, we investigate the crystalline properties (e.g. composition, crystallographic phases, lattice strain,and defects) based on the intensity distribution in the vicinity of a set of reciprocal lattice points.

 

By taking advantage of versatile measurement geometries and the high photon flux we can investigate e.g. structure-sensitive Bragg – reflections which provide unique insight in the evolution of polytypism when applied in-situ.

 

The in-situ investigation of growth processes with X-ray radiation provided by a synchrotron source is a challenging experimental task that requires both dedicated equipment and growth compatible non-destructive characterization methods. In our research we combine growth methods for achieving epitaxial nanostructures and non-destructive, time-resolved  X-ray scattering methods.

 

For the fabrication of the GaAs nanowires, we employ a portable molecular beam epitaxy (PMBE) system based at ANKA (KIT), which is dedicated for X-ray investigations at a synchrotron beamline during the growth process.

 

Previous topics of in situ investigations in these materials systems have included:

 

  • Investigation of strain and composition of InGaAs/GaAs during high temperature annealing by time-resolved grazing incidence X-ray diffraction
  • Determination of composition and strain of InAlGaAs/GaAs quantum dots by evaluation of coherent X-ray scattering features and comparison with numerical calculations

Selected Publications

 

K. Mostafavi et al., X-ray Diffraction Analysis of the Angular Stability of Self-Catalyzed GaAs Nanowires for Future Applications in Solar-Light-Harvesting and Light-Emitting Devices, Applied Nano Materials, 2019, 2(2), 689-699, DOI: 10.1021/acsanm.8b01677

 

P. Schroth et al., Radial Growth of Self-Catalyzed GaAs Nanowires and the Evolution of the Liquid Ga-Droplet Studied by Time-Resolved in Situ X-ray Diffraction, Nano Lett., (2017), https://dx.doi.org/10.1021/acs.nanolett.7b03486

 

D. Grigoriev et al., Asymmetric skew X-ray diffraction at fixed incidence angle: application to semiconductor nano-objects,  J. Appl. Cryst. 49, 961 (2016), https://dx.doi.org/10.1107/S1600576716006385

 

P. Schroth et al., Evolution of Polytypism in GaAs Nanowires during Growth Revealed by Time-Resolved in situ x-ray Diffraction, Phys. Rev. Lett. (2015), https://dx.doi.org/10.1103/PhysRevLett.114.055504

 

T. Slobodskyy, P. Schroth, D. Grigoriev, A. A. Minkevich, D. Z. Hu, D. M. Schaadt, and T. Baumbach: A portable molecular beam epitaxy system for in situ x-ray investigations at synchrotron beamlines. Review of Scientific Instruments 83, 105112 (2012); doi: 10.1063/1.4759495