Nanostructures, Materials & Devices for Information Technologies

The fabrication, processing and functionalization of materials based on nanostructures involves multiscale processes which often prohibit conventional characterization approaches. The penetration depth of X-rays, together with the brilliance of synchrotron radiation make X-ray scattering and diffraction techniques highly attractive for characterizing  these materials. Complementary to locally-resolving electron microscopy, these X-ray techniques give access to macroscopically representative statistical structure correlation properties at micro-, nano-, and atomic length scales. Using coherent diffraction imaging techniques even individual nano-objects can be investigated.

Current research within the general area of Nanostructures, Materials & Devices for Information Technologies includes:

 

Ultrafast Laser-based Nanomaterials Research

We use synchrotron radiation x-ray scattering and spectroscopy methods combined with laser-based ultrafast methods for the dynamic characterization of nanoscale matter, molecules and crystalline materials, in particular for the analysis of nanoscale dynamics, phonon excitation or phase transitions in the condensed phase.

 

Lattice dynamics, electronic and magnetic properties of thin-films

The broken translational symmetry at interfaces drastically modifies the atomic vibrations compared to their bulk counterparts. Understanding interface lattice dynamics is therefore of fundamental importance for basic and applied research. We currently investigate thermodynamic, elastic, electronic, and magnetic properties of e.g. silicide nanostructures, lattice dynamics of rare earth (RE) sesquioxides for applications as high-k dielectrics.

 

III-V-based nanostructures

Research focuses on the growth and characterization of semiconductor nanostructures in III/V materials systems. 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 grow self-catalyzed III/V nanostructures and characterize these using (in situ) X-ray scattering methods.

 

 Functional polycrystalline thin-film materials

Polycrystalline sputtered coatings are omnipresent in modern functional materials: they are found as anti-reflection coatings on eyeglass lenses, active layers in sensor chips, or hard coatings to extend the life of tools and medical implants. In situ X-ray measurements provide direct insight into the formation of the microstructure during sputtering, and contribute to growth models and an understanding of the interplay between microstructure and macroscopic material function.

 

Correlation of growth parameters and structure of epitaxial oxide thin films

Pulsed laser deposition growth of oxide thin films under in situ conditions to investigate the relationship between structure and measurable physical properties, such as dielectric, magnetic, ferromagnetic, and ferroelectric properties, in collaboration with other partners. The in situ PLD growth analysis covers a variety of materials and applications:
 

•    the role of growth parameters on defect formation in dielectric oxide materials 
•    determination of critical film thickness for domain formation during growth
•    in situ X-ray characterisation of crystal structure and defect changes during annealing and cooling
•    strain engineering of ferromagnetic films on different substrates
•    structural correlation of ferroelectric-ferromagnetic coupling in multiferroic materials

These activities build on the X-ray SCATTERING Cluster at IPS, with its state-of- the-art NANO beamline and experimental station equipped with heavy duty diffractometers for single crystal and powder diffraction, grazing incidence surface and interface scattering techniques, and at other synchrotron facilities such as ESRF, PETRA III, SOLEIL, and SLS.     

Dedicated in situ instrumentation, such as Pulsed Laser Deposition (PLD), Metal-Organic Vapor Phase Epitaxy (MOVPE), Molecular Beam Epitaxy (MBE), and sputtering, directly allow X-ray scattering experiments during thin-film and nanostructure formation. These studies are complemented by extensive surface and thin-film analysis facilities such as Reflection High-Energy Electron Diffraction (RHEED), Low-Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), XPS, as well as Atomic-Force Microscopy (AFM) and Scanning-Tunneling Microscopy (STM) at the IPS UHV-analytical lab.