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Most modern architectural glazing are coated with at least one low emissivity layer stack. As a consequence of deploying those coatings, the heat transfer through the glazing can be significantly minimized. The desired heat-insulating properties result from the low emissivity in the infrared (IR) achieved by employing a thin metal film. Consequently, the majority of industrially fabricated low emissivity coatings on glass feature a layer stack including a thin silver film. DC magnetron sputtering is the preferred fabrication process in the architectural glazing industry for the deposition of low emissivity films due to the inherent advantages of this fabrication process like the homogeneous and time-efficient coating of large glass substrates. Thus, all layers discussed throughout this work are deposited by magnetron sputtering. To improve the efficiency of these coatings, the emissivity in the infrared needs to be decreased. This is equivalent to a maximization of the IR reflectance. Due to a fundamental link between the IR reflectance and the electrical resistance, the intended efficiency improvement can be achieved by a reduction of the electrical resistance of the silver film. The application of seed layers, namely ZnO, is a known method to decrease the resistance. In this context, the zinc oxide is used as a template to tailor the texture of silver thin films. Hence, one goal of the present work is to investigate the corresponding interface of the standard Ag/ZnO system to improve the understanding of this layer stack and to identify ways to obtain silver thin films with an improved structural quality in the thickness range between 8 nm to 12 nm. In particular one of the main objectives is the analysis of the epitaxial relationship between Ag and ZnO. Hence, various analysis techniques are employed to characterize and gain new insights about this system. Primarily, these techniques comprise electrical and structural characterization methods to correlate the film resistance with the structural quality of the Ag film and its relation to the substrate. To this end, different transport measurements are utilized including temperature dependent resistance measurements, whereas the structural characterization focuses on x-ray diffraction and transmission electron microscopy. In addition, the influence of alternative seed layers on silver thin films is analyzed. Two suitable approaches for the modification of the silver structure have been identified and were tested. The first approach features the integration of an additional seed layer, namely NiO, whereas the second one is based on using hydrogen-passivated, (111) oriented silicon substrates for the silver deposition. In both cases, the focus is on the interplay between seed layer and functional silver film. Particularly, it has been analyzed whether the silver structure and the electrical properties can be improved by these alternative seed layers. In detail, it has been also tested if the texture can be changed and whether the different seed layers have a pronounced impact on the percolation limit of the silver thin film or not. |
