Abstract
In this work we introduce two new solar cell and module concepts based on halogen lamp recrystallised silicon thin-films. At Fraunhofer ISE we have been working on zone melting recrystallisation (ZMR) using halogen lamps for more than a decade. We are able to grow crystalline high quality (etch pit density 3x106 cm-2) silicon layers on areas larger than standard wafer sizes (meta-wafer) and with speeds of 350 mm/min which corresponds to a throughput of more than 5 m2/h in our equipment. Lifetime measurements with Microwave Photo Conductance Decay (MWPCD) show values of up to 7.2±1.5 µs for recrystallised layers on thermal SiO2 and 1.7±0.2 µs on c-SiC. The excellent quality of the layers for one led us to the development of a lift-off concept where the layers are processed on a perforated high-temperature stable substrate. First layers could be detached successfully though they are very brittle so far. Another new approach using the large area processing capabilities of c-Si thinfilms is the integrated, interconnected recrystallised silicon thin-film module called IntegRex. For this concept we start with a meta-wafer ceramic substrate. We could develop an industrially feasible process to separate the cell stripes with laser chemical processing. Both these concepts promise high efficiency and high cost-reduction potential.