Section Oxides & Fluorides

Section Oxides & Fluorides


The section specializes in the bulk growth of oxide and fluoride single crystals. Such crystals are used as substrates for ferroelectric and oxide electronic applications as well as optical, piezoelectric, or laser components. We also prepare reference and benchmark samples to enable studies on the properties of materials with highest structural perfection and purity. Through collaborations and service to companies and research institutions we provide the materials basis for many research projects inside and outside IKZ.

Research activities

In our section, we develop single crystal substrates of oxide semiconductors such as β-Ga2O3. We prepare oxide crystals with perovskite structure as lattice-matched substrates e.g. for strained ferroelectric layers or thin films comprising new functionalities. We research tailored oxide and fluoride crystals for optical applications and lasers. And we provide thermochemical analysis and develop tailored growth techniques to enable crystal growth of novel compounds.


Junior Research Group "Fluoride Crystals for Photonic Applications"

Fluoride single crystals are key components for a variety of photonics applications such as laser materials, high power optical isolators, as well as nonlinear frequency converters and optical windows with superior properties in the deep-UV region. Fluoride compounds can overcome the current limitation in handling power of optical isolators. They are also very promising for solid state laser cooling (optical refrigeration), a technique enabling to cool down solid materials to cryogenic temperature by laser excitation.

The Junior Research Group is particularly engaged in melt growth of high-quality fluoride single crystals doped with rare-earth ions for laser cooling. Main challenges are to mitigate formation of foreign phases and color centers and to minimize oxygen contamination and internal strain. Fluorination of raw materials helps to prepare highest purity crystals. The application-relevant properties of grown crystals are demonstrated in collaboration with the IKZ Center for Laser Materials.


Dr. Hiroki Tanaka

Ph. +49 30 6392 2821


Single Crystals of Oxide Semiconductors

We manufacture transparent conducting or semiconducting oxide single crystals. The topic is primarily known from our pioneering work on 2" β-Ga2O3 single crystals (Czochralski method), and other binary oxides (In2O3, SnO2). In recent years, we have developed gallium based spinels (MgGa2O4, ZnGa2O4, CoGa2O4), barium stannate (BaSnO3) and lanthanum indate (LaInO3). As substrates and thin films, these crystals enable new device structures in power electronics, optoelectronics, for sensors and ferrimagnetic thin layers, and as scintillator material.

The growth of these crystals is hampered by the tendency to decompose at high temperatures near the melting point. We therefore use novel and proprietary methods and technologies (e.g. dynamic gas atmospheres) to increase compound and growth stability to enable large crystal volumes. A special focus is on the control and characterization of the electrical and optical properties in dependence on growth, doping and annealing conditions.

Zbigniew Galazka
Transparent Semiconducting Oxides - Bulk Crystal Growth and Fundamental Properties
ISBN 9789814800945; Jenny Stanford Publishing, 2020

Zbigniew Galazka
Czochralski method
in: “Gallium Oxide, Material Properties, Crystal Growth, and Devices", Eds. M. Higashiwaki and S. Fujita
ISBN 9783030371531; Springer Nature Switzerland AG, 2020
DOI: 10.1007/978-3-030-37153-1_2

Zbigniew Galazka, Klaus Irmscher, Robert Schewski, Isabelle M. Hanke, Mike Pietsch, Steffen Ganschow, Detlef Klimm, Andrea Dittmar, Andreas Fiedler, Thomas Schroeder, Matthias Bickermann
Czochralski-Grown Bulk β-Ga2O3 Single Crystals Doped with Mono-, Di-, Tri-, and Tetravalent Ions
J. Cryst. Growth 529 (2020) 125297
DOI: 10.1016/j.jcrysgro.2019.125297


Dr. Zbigniew Galazka

Ph. +49 30 6392 3020


Substrate Crystals for Advanced Functional Oxides

Our primary focus is to develop new perovskite and pyrochlore crystals with tailored lattice parameters. As substrates, such crystals serve as the literal foundation for the preparation of epitaxially grown oxide thin films with interesting ferroelectric, superconducting, ferromagnetic, piezoelectric, multiferroic, or electron transport properties. Some of the bulk crystals are attractive for optical applications as well. Most of the compounds are exclusively grown at IKZ for our academic and industrial research partners.

The growth temperature is typically in the range between 1500°C and 3000°C. Depending on the material properties at such high temperatures and the requirements on structural quality and purity, the crystals are grown by crucible-based or crucible-free methods from the melt or from melt fluxes. Insufficient heat transport, internal strain in the crystals and crucible stability are critical issues that must be carefully controlled. The crystals are investigated by their structural quality and chemical composition.

Christo Guguschev, Julia Hidde, Thorsten M. Gesing, Mathias Gogolin, Detlef Klimm
Czochralski growth and characterization of TbxGd1xScO3 and TbxDy1−xScO3 solid-solution single crystals
DOI: 10.1039/C8CE00335A

Christo Guguschev, Zbigniew Galazka, Dirk J. Kok, Uta Juda, Albert Kwasniewski, Reinhard Uecker
Growth of SrTiO3 bulk single crystals using edge-defined film-fed growth and the Czochralski methods
DOI: 10.1039/C5CE00798D

Christo Guguschev, Detlef Klimm, Mario Brützam, Thorsten M. Gesing, Mathias Gogolin, Hanjong Paik, Andrea Dittmar, Vincent J. Fratello, Darrell G. Schlom
Single crystal growth and characterization of Ba2ScNbO6 – A novel substrate for BaSnO3 films
Journal of Crystal Growth
DOI: 10.1016/j.jcrysgro.2019.125263


Dr. Christo Guguschev

Ph. +49 30 6392 3124


Crystals for Benchmarking and Service

Individual single crystals are demanded as benchmark and reference materials in different fields of science, e.g. geology, materials science, solid-state chemistry and physics. They are used by research institutions, companies and technology ventures for detailed investigation, to demonstrate their application potential or to assess conditions for a commercial production. If the required material falls within our range of capabilities and is not commercially available, we can prepare and provide it.

We use thermochemical analysis to determine how a particular material can be best grown as a single crystal with desired properties. While our core area of research is melt growth at high temperatures, we can employ a variety of growth approaches and techniques. In-house characterization provides a thorough assessment of the crystals’ properties. Depending on the target and effort of the research, we can operate by joint development agreement, full-cost accounting or scientific collaboration.

Eric Langenberg, Dipanjan Saha, Megan E. Holtz, Jian-Jun Wang, David Bugallo, Elias Ferreiro-Vila, Hanjong Paik, Isabelle Hanke, Steffen Ganschow, David A. Muller, Long-Qing Chen, Gustau Catalan, Neus Domingo, Jonathan Malen, Darrell G. Schlom, Francisco Rivadulla
Ferroelectric domain walls in PbTiO3 are effective regulators of heat flow at room temperature
Nano Letters 19, 7901-7907 (2019)
DOI: 10.1021/acs.nanolett.9b02991

Florian Flatscher, Martin Philipp, Steffen Ganschow, Martin R. Wilkening, Daniel Rettenwander
The natural critical current density limit for Li7La3Zr2O12 garnets
Journal of Materials Chemistry A 8, 15782-15788 (2020)
DOI: 10.1039/c9ta14177d

E. Bertoldo, A. H. Abdelhameed, G. Angloher, P. Bauer, A. Bento, R. Breier, C. Bucci, L. Canonica, A. D'Addabbo, S. Di Lorenzo, A. Erb, F. V. Feilitzsch, N. Ferreiro Iachellini, S. Fichtinger, D. Fuchs, A. Fuss, P. Gorla, D. Hauff, M. Ješkovský, J. Jochum, J. Kaizer, A. Kinast, H. Kluck, H. Kraus, A. Langenkämper, M. Mancuso, V. Mokina, E. Mondragon, M. Olmi, T. Ortmann, C. Pagliarone, V. Palušová, L. Pattavina, F. Petricca, W. Potzel, P. Povinec, F. Pröbst, F. Reindl, J. Rothe, K. Schäffner, J. Schieck, V. Schipperges, D. Schmiedmayer, S. Schönert, C. Schwertner, M. Stahlberg, L. Stodolsky, C. Strandhagen, R. Strauss, I. Usherov, M. Willers, V. Zema, J. Zeman, M. Brützam, S. Ganschow
Lithium-containing crystals for light dark matter search experiments
Journal of Low Temperature Physics 199, 510-518 (2019)
DOI: 10.1007/s10909-019-02287-3


Dr. Steffen Ganschow

Ph. +49 30 6392 3024