Stress-driven architectures and phenomena
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Part of the research area concentrates on micro-/nanostructures driven by stress relaxation in ultra-thin films. These can be highly strained layers which roll-up into micro- and nanotube structures, once the layers are released from the substrate surface, or quantum dot heterostructures spontaneously forming during lattice mismatched epitaxy. Although this technology relies on a self-assembling process, position, size, shape and functionality of these novel objects can be accurately controlled on a single chip by deposition, lithography and etching technologies. The technology of “shaped nanomembranes” will be extended to a wide range of materials for optical, magnetic, electronic, fluidic, or biological applications. This requires detailed analysis of structural properties and formation processes. The integration of these micro- and nanostructures into existing technological platforms and process flows seams feasible, and the development of novel devices like minute engines and fluidic networks for bio-analysis as well as flexible optical ring resonators and x-ray waveguides are in progress. Another part of studies puts emphasis on phenomena and applications based on stress generation on surfaces and in materials. This includes multiferroic thin film systems with large magnetoelectric coupling, which is based on reversible elastic strain transfer between the components as well as surface acoustic waves deriving from periodic surface strains. Surface acoustic waves components are used in sensors and as frequency filters for the channel selection in signal transition. They consist of a piezo-electric single crystal chip which transforms electric signals in acoustic ones and back. The IFW has contributed a number of innovations in this field, for example a considerable improvement of temperature stability and of electromechanical excitation by a special thin film material. Heterogeneous Multiferroica3D Micro- and NanoarchitecturesQuantum DotsSAW systems |