Processing of C-SI Thin-Film Solar Cell on Ceramic Substrate with Conductive SIC Diffusion Barrier Layer

All work published so far on C-SiTF on ceramics was based on either non-conductive ceramics, or on "model" ceramics never able to cope with the cost requirements. For a wafer equivalent approach, where c-Si films on substrate can be directly processed to solar cells with nowadays technology, the respective substrates however need to be low-cost and electrically conductive. We therefore decided to use tape-casted RBSiC (Reaction Bonded) ceramics as a cost-effective substrate which can be used in a production scenario without any further change. The porosity present in this substrate material causes special problems during layer and solar cell preparation. We realized multicrystalline Si thin-films with high quality on these substrates. Here we report our experience and results on the way to prepare the films and in further solar cell processing. We firstly present results concerning SiC diffusion barrier performance. The concentration of transition metals in our cell bulk was measured by Glow Discharge Mass Spectrometry (GDMS). The data show a significant concentration decrease of 3 to 4 orders of magnitude for Fe, V and Co from substrate to cell bulk. The second focus of this work is the porosity of the ceramic substrate. We were able to observe on cross sections that the pores are filled with Si and the intermediate layer (IL) covers their inner surface. Furthermore the applicability of several industrial cell process steps was tested. Especially plasma processes for texturization were realized and led to promising results. Solar cell results of cells with an area of 1 cm will be presented