The group focuses on characterization of structure and composition of both crystalline and amorphous materials including monocrystals, thin films and nano-structures. In the research, we employ large variety of X-ray scattering and spectroscopic methods both in home laboratory and at synchrotron facilities. The strength of the group lies in combining condensed matter physics and X-ray scattering theories with our ability to build and adapt X-ray instruments and to write own analytical software for experimental data interpretation. Additionally, several group members deal also with growth of thin films.
We have a long-time expertise in a broad range of X-ray scattering and spectroscopy methods:
- X-ray diffraction (XRD)
- Powder X-ray diffraction
- Grazing-incidence X-ray diffraction
- X-ray topography
- X-ray reflectometry (XRR)
- Small-angle scattering techniques (SAXS, GISAXS)
- X-ray imaging
- The X-ray techniques are applied in-situ in a large variety of sample environments to study structural properties of materials:
- during annealing and at cryogenic conditions (temperature range from 10 K to 1200 K)
- in magnetic fields
- for thin films at liquid surfaces
- during thin film growth in real-time
- Thin film growth using pulsed laser deposition (PLD), organic molecular beam deposition, Langmuir-Blodegett technique, and spin coating
We develop these X-ray methods and apply them for:
- Characterization of crystal structure perfectness and homogeneity (e.g. semiconductor samples).
- Defects in crystals, including grains, dislocation density, lattice misorientation etc. (silicon and semiconductor wafers, such as GaN, SiC, GaAs; topological insulators; etc.).
- Determination of thicknesses of layers and interface roughness (thin films, multilayers and superlattices, amorphous as well as crystalline).
- Shape and size distribution of small particles, size up to 400 nm (quantum dots, nano-particles, biomolecules, etc.).
- Determination of crystal faces orientation.
- Sample structural changes during annealing, cooling, application of magnetic field.
Selected list of current research topics of the group:
- Characterization of semiconductor wafers (e.g. Si, GaN, SiC) and epitaxially grown semiconductor multilayers (e.g. Si/Ge, GaN/AlN) for industry and basic research.
- Structure of topological insulators (e.g. BiTe, BiSe).
- Structure of quantum dots (e.g. GaAs, AlGaAs).
- Structure of thin films of organic semiconductors and of mechanisms of their growth.
- Growth and structure of nano-particles in solutions.
- Characterization of large arrays of semiconductor micro-pillars (Ge on Si, GaAs on Si, SiC on Si, etc.).
- Simulations of X-ray crystal optics set-ups.
History of the group
In late 60's and 70's of the 20th century, the department X-ray laboratory studied mainly monocrystals, powders and semiconductor materials using X-ray diffraction and X-ray diffraction topography methods. Later in 80‘s, the growing research group started to reconstruct the diffractometer set-ups using up-to-date 8bit computers, thus having the first computer-drive diffractometers in the central Europe. Further, everybody in the group got experienced with writing analysis software. Currently, we are still running our self-assembled and optimized diffractometers as well as modern commercial ones with built-in software. Therefore, it is not a problem to us to tune either of these diffractometers to specific purposes, write our own simulations and data analysis software for the best sample structure modeling.
Last but not least, we have long-time experience with synchrotron measurements, applying X-ray scattering, X-ray spectroscopy and imaging techniques. Until now, we were running experiments at most the European synchrotrons, including ESRF, BESSY, HASYLAB, Swiss Light Source, Diamond, Elettra, Solaris, etc.