The influence of oxygen and nitrogen impurities on the performance of thin-film solar cells based on microcrystalline silicon (mu c-Si:H) has been systematically investigated. Single mu c-Si:H layers and complete mu c-Si:H solar cells have been prepared with intentional contamination by admitting oxygen and/or nitrogen during the deposition process. The conversion efficiency of similar to 1.2 mu m thick mu c-Si: H solar cells is deteriorated if the oxygen content in absorber layers exceeds the range from 1.2 x 10(19) to 2 x 10(19) cm(-3); in the case of nitrogen contamination the critical impurity level is lower ([N](critical)=6 x 10(18)-8 x 10(18) cm(-3)). It was revealed that both oxygen and nitrogen impurities thereby modify structural and electrical properties of mu c-Si:H films. It was observed that the both contaminant types act as donors. Efficiency losses due to oxygen or nitrogen impurities are attributed to fill factor decreases and to a reduced external quantum efficiency at wavelengths of >500 nm. In the case of an air leak during the mu c-Si:H deposition process, the cell performance drops at an air leak fraction from 140 to 200 ppm compared to the total gas flow during i-layer deposition. It is demonstrated that oxygen and nitrogen impurities close to the p/i-interface have a stronger effect on the cell performance compared to impurities close to the n/i-interface. Moreover, thick mu c-Si:H solar cells are found to be more impurity-sensitive than thinner cells

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Different layer architectures produced by only MOD, only MOCVD and combinations of MOD buffers and MOCVD YBCO are presented. RTR MOCVD-YBCO layers obtained on MOD CeO 2 MOD LZO Ni5at%W tapes demonstrate critical current densities up to 2 MA cm 2 at 77 K. On single LZO (50-100 nm) buffered Ni5at%W tapes from Nexans Superconductors and on RTR MOCVD buffer layers critical current densities between 0.8 and 1.3 MA/cm are obtained. RTR MOD-LZO layers often show delamination during YBCO deposition. Preannealing treatment before YBCO deposition allows to avoid this. Tapes up to 10 m are produced by combination of MOD-LZO and RTR MOCVD-YBCO.

The miniaturisation of mechanical components and machines enables innovative future products. However, for the improvement of functionality, reliability and lifetime of those micro systems, micro tribological coatings with thicknesses in the sub-micron range are needed. To cover these needs, we investigated different submicron coatings with the aim to develop wear and friction optimized thin films for this application. The basis of this work has been the state of the art know how of well established macroscopic coatings which in general are in a thickness range of a few micrometers. It turned out, that particularly the surface topography and the substrate material influence the properties of very thin films. For investigations with single asperity contact, the coefficient of friction (COF) was reduced by lowering the tip radius and the hardness of the substrate material. In contrast, for larger contact radii (pin-on-disc), an increase of the COF with decreasing substrate Young's modulus was found. With respect to wear, it turned out that the wear depth increased dramatically with increasing initial surface roughness (R(ind a))

An important aspect of the development of electromagnetic microactuators is the search for suitable materials as well as the development of the respective deposition and patterning processes. Within the Collaborative Research Center 516 "Design and Fabrication of Active Microsystems", it is the task of the subproject B1 "fabrication of magnetic thin films for electromagnetic microactuators" to perform these investigations. The materials of interest can be divided into two groups: hard magnetic materials and soft magnetic materials. Materials with optimized properties and fabrication processes have been developed within both groups. An example is Samarium-Cobalt (SmCo), which can either be deposited using magnetron sputtering as Sm2Co17 with a very high energy product or in the SmCo5 phase using gas flow sputtering with very high deposition rates. In the area of soft magnetic materials, investigations on Nickel-Iron (NiFe) especially NiFe81/19 were followed by the evaluation of NiFe45/55, which features a higher saturation flux density B (s) and relative permeability mu (r). Furthermore, current investigations focus on Cobalt-Iron (CoFe) and its further increased saturation flux density B (s) and relative permeability mu (r). Current tasks include the stabilization of the fabrication processes to achieve good material properties (i.e. electroplating of CoFe) or a shortening (e.g. by using heated substrates during deposition) by using process alternative not used so far. Another topic is the integration into fabrication processes, i.e. the investigation of process stability and compatibility