In this work, we present a technology for a high precision nanostructure replication process based on ultraviolet nanoimprint lithography for the application in the field of thin-film photovoltaics. The potential of the technology is demonstrated by the fabrication of microcrystalline silicon thin-film prototype solar cells. The high accuracy replication of random microstructures made from sputtered and etched ZnO:Al, used to scatter the incident light in thin solar cells, is shown by local topography investigations of the same 7.5 Â 7.5 mm 2 area on the master and the replica. Different types of imprint resists and imprint moulds were investigated to find the optimal, high precision replication technology. Two types of thin-film silicon solar cells, in p-i-n and n-i-p configuration, were fabricated to study the potential of the imprint technology for different applications. It is shown that solar cells deposited on an imprinted glass hold similar performances compared with reference solar cells fabricated with a standard process on textured ZnO:Al. Thus, it is demonstrated that the replication of light scattering structures by using an imprint process is an attractive method to decouple the scattering properties from the layer forming the electrical front contact. Because a simple and cheap high throughput process is used, this study additionally proves the relevance for the industrial mass production in the field of photovoltaics.
The pulsed laser deposition (PLD) technique is an excellent method to prepare single crystalline complex oxide thin ®lms. We have successfully grown ®lms for the use in HTS SQUID-devices as well as for thin ®lm optical waveguides. The Josephson junction used in the HTS SQUIDs is formed by a step edge type grain boundary junction. The step preparation is a very critical process in the SQUID preparation to achieve reproducible low 1/f noise devices. We have established a new ion beam etching process to achieve clean and steep edges in LaAlO 3 (1 0 0) substrates. The 1/f noise of SQUIDs prepared with the new method is drastically reduced. In the process of developing thin ®lm electro-optical waveguide modulators we investigated the in¯uence of different substrates on the optical and structural properties of epitaxial BaTiO 3 thin ®lms. These ®lms are grown on MgO(1 0 0), MgAl 2 O 4 (1 0 0), SrTiO 3 (1 0 0) and MgO buffered Al 2 O 3 (1 1 0 2) substrates. The waveguide losses and the refractive indices were measured with a prism coupling setup. The optical data are correlated to the results of Rutherford backscattering spectrometry/ion channeling (RBS/C), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The dielectric constant, the ferroelectric hysteresis loop and the transition temperature (ferroelectric to paraelectric state) of the BaTiO 3 thin ®lms are measured. #
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