Project

Discipline

Pulsed Laser Deposition; Oxide thin films; Strain and growth control; Thin Films; Complex Oxides; in-situ Growth Control

Lead
Lay summary
One of the most versatile deposition techniques in solid state physics and analytical chemistry is the vaporization of a solid or soft material using photons. Condensing the vaporized material on a surface enables the growth of thin layers with defined properties which requires a sophisticated control of the vapor composition and growth conditions.For the laser vaporization of matter, a short-pulsed high-power laser beam is focused onto a sample surface thereby converting a finite volume of a material instantaneously into its vapor phase constituents such as ions and neutral species. Subsequently, the vapor moves away from the target at a high velocity and can be sampled either to grow a film or being analyzed by various spectroscopic techniques. Pulsed laser deposition is conceptually a simple deposition tool for thin films growth and assembling artificially layered materials. Its main advantage is that almost any complex material like multicomponent oxides can be evaporated and hence grown as a thin film. However, to grow films and multilayers with defined properties, an appropriate in situ monitoring of growth parameters during the deposition is required. At present the most advanced analysis tools can give information on an atomic level and the growth progress is monitored instantaneously.Growth induced strain is an inherent consequence of thin film growth. It can profoundly affect the materials physical properties like electrical conductivity or magnetism. This is particularly true for multicomponent oxide thin films where strain can even be beneficial in order to enhance physical properties well beyond the natural limits of a compound. To quantify strain during growth, an optical detection system will be used which measures the strain induced distortion of a growing film. The influence of strain on thin film properties is not well understood at present. Therefore an in situ quantification of strain will produce films with defined strain properties allowing for defined correlations with respective film properties. A precise monitoring of growth conditions and thin film strain at the same time will benefit the quality of materials research conducted and the approach to thin film growth, in particular when dealing with new materials not available in nature. An advanced control over deposition conditions and hence materials properties will be a key requirement to unravel and explore phenomena which e.g. take place at interfaces of two materials grown on top of each other.

Direct link to Lay Summary

Last update: 21.02.2013

Number	Title	Start	Funding scheme

We propose the purchase of a new pulsed laser deposition system with the main purpose to deposit high quality ceramic thin films and multilayers for materials and physics research with the instrumental option to monitor in-situ their substrate induced strain and growth. The system should be equipped with an in situ stress monitoring system, a high pressure RHEED, quartz microbalance and Langmuir probe. The proposed deposition chamber is intended to be a vital fabrication and research tool for advanced ceramic thin film and multilayer deposition for materials research. Over the past years the improvement in oxide thin film deposition and experimental requirements have advanced significantly. In order to keep up with the demand of crystalline quality for thin films and multilayer an adequate in-situ growth diagnostics becomes mandatory combined with the need to try new pathways for materials development not accessible to bulk materials. The controlled utilization of strain in thin films to tune materials properties is an important future research topic in thin films materials research. At PSI, there are several dedicated laser ablation set-ups (Materials Science beamline, Surface and Interface Spectroscopy beamline, Materials group at ENE) providing high quality samples for various research activities at SYN, NUM and ENE, likewise ETH and EMPA with the aim to study the behaviour of complex thin films and multilayers, multiferroic materials, and functional materials for energy applications. A new deposition chamber with advanced in situ diagnostics of crystallinity and strain during growth would therefore present an indispensible tool to research and development of new materials and materials combinations, like artificial multilayers to develop new and hopefully more efficient membranes for solid oxide fuel cell or thermoelectric structures based on oxide materials. Such an investment is intended to establish interdepartmental projects and to encourage synergistic research in the area of materials research and development.Research projects discussed in the proposal which have an immediate use of such a laser ablation chamber are:Renewable energy applications and the respective materials development for ion conducting membranes of Y-stabilized ZrO2 (YSZ) applied to solid oxide fuel cells (Prof. L. Gauckler, Department of Materials, ETHZ).Growth of single layers and heterostructures of novel functional oxides relevant for thermoelectric applications (Prof. A. Weidenkaff, Solid State Chemistry and Analyses Laboratory, EMPA).Active strain control of thin film model electrodes on substrates relevant for Li-ion batteries to study in a clean system the electrolyte-electrode interaction during the electrochemical cycling (Prof. P. Novak, Battery Sections, PSI).Effect of strain on the physical properties of natural and artificial multiferoic thin films and multilayers (Dr. M. Kenzelmann, Laboratory for Materials Development, PSI; Dr. C. Niedermayer, Laboratory for Neutron Scattering, PSI). Magnetism at LaAlO3/SrTiO3 conducting interfaces and local magnetism of orthorombic TbMnO3 thin films (Dr. E. Morenzoni, Laboratory for Muon Spin Spectroscopy, PSI).Manganite multiferroics thin films to investigate orbital and magnetic order (Dr. U. Staub, Swiss Light Source, PSI)Preparation of artificial multiferroics to study their magnetic structure using synchrotron radiation (Prof. F. Nolting, Dr. L. Hayerman, Swiss Light Source, PSI).Preparation of manganite thin films with a charge order transition for time-resolved fs x-ray spectroscopy (Dr. G. Ingold, Swiss Light Source, PSI).