Our goal is to use and develop synchrotron-based X-ray techniques to study the real structure of single crystals on all scales. Recent development of 4th generation synchrotron radiation sources and instrumentation offers new approaches to study crystalline materials from atomic via nano- towards macroscopic scale. Using X-rays is paramount for experiments on crystals in-situ (e.g. during growth, treatment or operation) and this way provides a deep insight into dynamics and transitions of crystal structures.

We study real structure of crystals and its impact on materials properties as a function of various environmental parameters. This spans from analysis of atomic displacements that define how crystals behave under influence of external fields, to imaging of lattice inhomogeneities that affect optical or electronic characteristics of semiconductor materials and contain information about local stoichiometry. Such imaging methods are ideal to correlate crystal structure and function within recent semiconductor devices.

The electron microscopy group focuses on the relation between physical properties and structure of semiconductors and oxides and of epitaxial materials by cutting edge electron microscopy techniques. By discovery of novel phenomena, their fundamental understanding and by developing predictive models we aim at improving the materials perfection and open perspectives for their technological applications. To reach these goals we combine the whole spectrum of structural and analytical techniques and are engaged in methodological developments.

We study real structure of crystals and its impact on materials properties as a function of various environmental parameters. This spans from analysis of atomic displacements that define how crystals behave under influence of external fields, to imaging of lattice inhomogeneities that affect optical or electronic characteristics of semiconductor materials and contain information about local stoichiometry. Such imaging methods are ideal to correlate crystal structure and function within recent semiconductor devices.

Using state-of-the-art X-ray techniques, we aim to achieve a fundamental understanding of the correlation of structural and physical properties in crystalline materials. These investigations will also contribute to improving material perfection and pointing out paths for possible technological applications. For this purpose, we have a number of highly specialized instruments at our disposal at IKZ, including sophisticated experiments at synchrotron radiation sources.

Besides the determination of crystal orientation and crystal phases, we are primarily concerned with the elucidation of the real structure in bulk crystals and epitaxial layer systems. For ferroelectric thin films, we aim at a fundamental understanding of phase and domain formation, whereby phase transformations are identified and characterized by complex in situ experiments.  For the verification of real structure models, corresponding simulations are developed.

Establishing the dynamic process-structure-function relationships under realistic conditions at relevant length and time scales are essential for achieving groundbreaking advancements in material science.

The In Situ TEM Group is committed to advancing materials science by visualizing, understanding, and controlling correlated chemical, structural, and electronic changes from the micro to atomic scale using in situ and operando TEM techniques. FAIR principles and AI will be implemented to streamline the workflows, standardize the procedures and enhance knowledge sharing among scientists.

Ultimately, we aim to expedite scientific discovery and drive innovation in materials science, positioning us in the forefront of the field.

We are committed to advancing the understanding and development of the electronic and photonic materials at IKZ and of our collaborative partners, leveraging through the power of  in situ TEM techniques. Our research focuses on analyzing the fundamental aspects of phase transformation in oxides and uncovering the dynamics that govern the behavior of  memristive materials for neuromorphic computing, LEDs, SiGe-based qubits for quantum computing under operational conditions. To achieve this, we employ a suit of cutting-edge TEM techniques, including HRTEM, HAADF, DPC, iDPC, EDS, EELS, 4DSTEM. Complemented by MEMS-based in situ TEM platforms, in situ TEM allows us to delve into dynamic changes of elemental distribution, strain, polarization, bandgap, electric field and other relevant parameters down to the atomic scale. Simultaneously, the electric or optical properties will be measured in a parallel fashion.

In addition to material studies; we also engage in methodological innovations, including advanced FIB sample preparation techniques, on chip calorimetry, correlative data analysis among others. To ensure the integrity of our findings, we rigorously assess potential non intrinsic modifications to the materials, such as those induced by electron beam irradiation, as well as any discrepancies between TEM sample and operational device geometry. This comprehensive approach aims to provide a thorough understanding of the underlying mechanisms spanning from fundamental research to industry-level material development initiatives.

Control over the electrical conductivity of semiconductor crystals is essential prerequisite to realize the semiconductor devices needed in modern electronics. To assess the electrical properties of the semiconductors grown at IKZ we use current transport and capacitive measurements to determine, e.g., the concentration and mobility of free charge carriers, the concentration of dopants and that of compensating impurities or defects in close relation to growth and doping conditions.

Conductivity and Hall effect measurements (20-1100 K), deep level transient spectroscopy (20-800 K) and photo-thermal ionization spectroscopy as well as appropriate contact preparation techniques are continuously adapted and extended to meet the different requirements the various semiconductor crystals impose, e.g., additional photoexcitation for wide-bandgap semiconductors. Our present focus is on semiconducting oxides with potential for power electronics and resistive switching.

Our mission is to gather a detailed understanding of fundamental physical properties of bulk crystals and thin films. In this context, optical spectroscopy represents a highly versatile analytical characterization tool. We focus on the investigation of optical processes, which hold information about material-specific properties. This includes intrinsic characteristics of the system, such as band gaps or vibronic states, as well as extrinsic properties related to structural- or point defects. We are conducting research on novel crystal systems that have been grown in-house, as well as those supplied from collaborating partners.

Currently, the materials under investigation comprise novel oxides for memristive applications, as well as III-Nitrides for optoelectronics. To study their physical properties, we have a variety of experimental methods at our disposal. Next to widely used techniques such as emission-, absorption-, Raman spectroscopy, we also perform high spatial resolution cathodoluminescence spectroscopy. In addition, self-developed systems offer the possibility of measuring parameters which are experimentally difficult to access. This includes transmission spectroscopy of volume crystals at very high temperatures > 1000°C for studying the temperature dependence of bandgaps or defect absorption bands. Moreover, for detecting inhomogeneities in large volume crystals, we apply 3D tomographic analysis of scattered light.