Aim of Research
The aim of the Chair MEMS Materials is to efficiently discover and optimize new, economically interesting materials using combinatorial thin film deposition techniques and high-throughput characterization tools. The research is driven by the demand from industry for new and better materials.
The research focuses particularly on the development of thin film materials for microsystems (ferromagnetic thin films, shape memory thin films, ferromagnetic shape memory thin films) and materials for hydrogen storage.
The idea of combinatorial materials science is to develop and use advanced materials fabrication methods which produce a large number of different materials on a substrate in one experiment under identical conditions.
After the combinatorial deposition process the material libraries are screened for desired physical properties by adequate high-throughput characterization tools. Most effectively the screening is performed by parallel (e.g. optical) or fast sequential methods.
By using the combinatorial materials science approach, an accelerated development of new materials can be expected.
Research
The research of the Chair MEMS Materials is based on the application of combinatorial thin film deposition methods and high-throughput characterization-tools. Beside the further development of combinatorial thin film deposition methods, the design and realization of new high throughput characterization tools is a goal of the CMS group. The new concepts for high throughput characterization are based on MEMS and nanotechnology approaches.
These methods are used in order to identify and optimize new materials, which are suitable for industrial applications. The group focuses on materials for microsystems (magnetic, shape memory) and materials for hydrogen storage.
Combinatorial thin film deposition methods
The fabrication of thin film libraries by combinatorial thin film deposition methods can be divided in several categories:
1. Precursor deposition method
2. Co-deposition method
3. Deposition of wedge type films
At the combinatorial materials science lab of the Chair MEMS Materials, a unique UHV combinatorial cluster sputter deposition system is used. It allows the usage of all three methods for depositing optimized materials libraries.
High-throughput characterization of materials libraries
After the deposition of a thin film library, the screening for spots which show the desired physical properties has to be performed in an effective way. Generally, parallel or serial screening methods for thin film libraries can be applied depending on the physical property which is measured.
The chemical composition of individual spots on the thin film library can be determined by automated EDX (energy dispersive x-ray spectroscopy). The figure shows the Al distribution in a Fe-Co-Al composition spread measured at 301 spots.
In order to determine whether the materials on the library are crystalline or amorphous, or to distinguish different crystallographic phases, automated XRD (x-ray diffraction) is used. To clarify structure-property relations, samples for the analysis of the nanostructure in the TEM (transmission electron microscope) can be rapidly prepared by automated FIB (focused ion beam).
Special physical properties
An automated 4-point probe for the measurement of temperature-dependent magneto-electronic properties was developed.
It is used for Wafer-Mapping of:
- temperature dependent resistivity
- temperature dependent Kerr effect
- temperature dependent magneto-resistance
Furthermore several screening techniques based on MEMS wafers (cantilever-, membrane-, electrode-, micro-hotplate) are currently developed for combinatorial materials science experiments.
Links to other Research Groups
USA:
Prof. Takeuchi, UMD
NIST
Europe:
Prof. Maier, Lehrstuhl für Technische Chemie