In recent years, manifold findings in complex oxides (e.g. perovskites) have led to lots of attempts to search for new physics in this material class. In this regard, SrTiO3 as a prototype is of particular interest. For establishing SrTiO3 and related perovskite oxides for electronic applications, a fundamental understanding of growth process and resultant defects, oxygen vacancies and interface phenomena are essential prerequisites. However, in spite of many experimental and theoretical efforts, this understanding is still limited yet. Therefore, this subproject aims to investigate epitaxial film growth of SrTiO3 thin films in dependence of growth parameters and choice of the substrate. Systematic studies on point defects (e.g. oxygen and cation vacancies), electronic transport, role of hydrogen or metal-oxide interfaces are still lacking and will benefit from materials with high perfection and controlled doping.
Deposition of oxide films by the metal-organic chemical vapor deposition (MOCVD) technique promises a higher material perfection in view of lower defect density, smoother surfaces and interfaces, lower vacancy density (especially oxygen) compared to pulsed laser deposition (PLD). However, due to the poor availability of suitable MO precursors reproducible growth of complex oxides by MOCVD is still challenging yet. Based on the long-term cooperation with the associate partners at RUB, the aim of the project is to set a new state of the art in crystalline perfection and defect control of SrTiO3 films. Due to the lack of single crystalline films described in literature and unintended carbon incorporation (caused by the MO precursors), low defect films will be still a challenge. The additional use of PLD as physical deposition technique allows applying for a large range of deposition parameters, especially the oxygen partial pressure and the particle energy.
Major accomplishments expected:
Intentionally undoped and doped SrTiO3 thin films are grown homoepitaxially on SrTiO3 substrates. Apart from intrinsic doping by oxygen vacancies, extrinsic donors are incorporated in the form of aliovalent donors (e.g. Nb, La). In a second step, by an appropriate choice of the deposition conditions, growth on lattice matched substrates provide single crystalline films in 2D growth mode with low defect density and stoichiometric composition. Within the project, the preferential growth method is MOCVD, because this method enables better ordered and nearly stoichiometric films.
Collaboration with partners in the project:
We are collaborating with regard to the following topics
Aykut Baki is originally from a small town near Stuttgart, where he started studying materials science at the University of Stuttgart in cooperation with Max-Planck Institute for Solid State Research and Intelligent systems. During his Master studies at Technical University Berlin and Helmholtz-Zentrum für Materialien und Energie Berlin he investigated on oxide perovskites for energy recovery applications. Being part of GraFOx is an exciting opportunity for him to work in the promising and pioneering field of oxide electronic materials.
If you have queries about the project, please contact the PI:
Jutta Schwarzkopf, Institut für Kristallzüchtung
The Leibniz ScienceCampus GraFOx is a network of two Leibniz Institutes, two universities and one institute of the Max Planck Society. It is based in Berlin, Germany.
Paul-Drude Institut für Festkörperelektronik (PDI)
Leibniz-Institut im Forschungsverbund Berlin e.V.
Tel.: +49 30 20377-342
Prof. Dr. Henning Riechert, PDI
Dr. Oliver Bierwagen, PDI
Dr. Martin Albrecht, IKZ