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PublicationEmpowering Robots for Multimodal Tactile Gripping using Capacitive Micromachined Ultrasonic Transducers( 2021)
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PublicationFunctional integration - structure-integrated wireless sensor technology targeting smart mechanical engineering applications( 2018)Functional integration on the micro/nano scales enables smart functionalities in mechanical engineering systems. Here, exemplarily shown for a ball screw drive, a structure-integrated wireless sensor technology is implemented into a manufacturing system for advanced process control and status monitoring - even at machine components being not yet accessible or difficult to access. This includes also a miniaturized, networked and energy-efficient information and communication technology (ICT) integrated into the machine.
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PublicationPulse plating of manganese oxide nanoparticles on aligned MWCNT( 2015)
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PublicationDevelopment of new transparent conductors and device applications utilizing a multidisciplinary approach( 2010)Transparent and conductive films are key components for optoelectronic devices. They are applied as n-type transparent electrical contacts for inorganic and organic light emitting diodes, solar cells and flat panel displays as well as p- and n-type active semiconductive oxides to setup wide band gap-p-n junctions and devices for the emerging field of transparent and radiation hard electronics. The demand for these films is strongly increasing due to the extensive market growth in these areas but the solutions available today only partially fulfill the requirements on low resistivity, high transmittance, large area deposition, low cost manufacturing, and ability for fine patterning, light scattering and precise alignment of the electronic structure to surrounding semiconductors. The cooperation of five Fraunhofer Institutes within the "Fraunhofer Project MAVO METCO" aims towards establishing fundamental knowledge and control about the defect chemistry, structure and morphology of the transparent semiconductive oxides. The goal is to achieve materials with outstanding properties such as n-type transparent conductive oxides with tailored work function and excellent durability, novel delafossite based p-type materials allowing cost effective large area deposition, oxide based p-n heterojunctions and Ag based electrodes to be used for thin film photovoltaics and organic light emitting diodes. Starting from first-principle modelling of the electronic structure, we address the development of new transparent conductive layers by PVD and Sol-Gel ending up with device implementation for OLEDs and organic as well as Si based a-Si:H/µc-Si:H and HIT solar cells.
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PublicationA multidisciplinary approach towards advanced transparent conductive electrodes( 2009)The demand for transparent electrodes to be applied as electrical contacts for inorganic and organic light emitting diodes, solar cell and flat panel displays is strongly increasing due to the extensive market growth in these areas. The solutions available today only partially fulfil the demands on low resistivity, high transmittance, large area deposition, low cost manufacturing, ability for fine pattering, light scattering and precise alignment of the electronic structure to surrounding semiconductors and metals. The cooperation of five Fraunhofer institutes aimts towards achieving fundamental knowledge and control about the defect chemistry and morphology of the transparent semiconductive oxides to manufacture materials and devices with outstanding performances. Starting from the first principle material simulation using the density functional theory, we investigate into the effect structure of polycrystalline TCOs and TCO metal interfaces to identify relevant dopants for n-and p-type conductivity and the impact of the polycrystalline crystal structure on doping. The deposition of the TCO films is either by PVD or by Sol-Gel deposition. Using Sol-Gel we achieve transparent and conductive ZnO:Al films with resistivity of 1600 µcm as well as patterned ITO films by Sol-Gel printing of OLED manufacturing. Deposition of p-type conductive films by Sol-Gel on soda lime glass has been achieved by the first time for CuCrO2 and CuCr1-xAlx: Mg films. Sputter deposition of p-type CuCrO2 has shown to be successful using the novel technique of hollow cathode gas flow sputtering (GFS). The new method of high power pulse magnetron sputtering (HIPIMS) is used for the deposition of n-type TCOs with improved properties in terms of doping efficiency, ultra smooth surface morphology and excellent chemical durability. Magnetron sputtering of insulator-metal-insulator stacks (IMI) is utilized for low cost organic solar cell manufacturing where the adjustment of work unction and corrosion resistance is crucial for the performance of the device. Furthermore, we report in TCO development for Si based HIT solar cells and a-Si:H / c-Si:H tandem cells with improved light management and on OLEDs for lighting application using Ag or ZnO:Al based transparent conductors and printed TCOs.
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PublicationDevelopment of advanced transparent conductive electrodes for large-area opto-electronic devices( 2008)The need for transparent electrodes as electrical contacts for inorganic and organic light emitting diodes, solar cells and flat panel displays is strongly increasing due to the extensive market growth in these areas. The solutions available on the market today fulfill the demands on low resistivity, high transmittance,large area deposition,low cost manufacturing,and ability for fine patterning, light scattering and precise alignment of the electronic structure to surrounding semiconductors only partially. The coopereration of five Fraunhofer Institutes aims towards achieving fundamental knowlegde and control about the defect chemistry and morphology of the transparent semiconductive oxides to manufacture materials with outstanding proterties such as ZnO:Al film with doping efficiency >80%, n-type TCO films based on TiO2:Nb and Zn-stannates and Ag-based multilayers. New TOCs will be developed using advanced PVD and Sol-Gel techniques. Using these new materials for device applications, we expect a strong impact towards more advanced and more efficient products. First results of our work addressing band structure simulation, material and process development will be shown.
