Thin film solar cells prepared on low thermal budget polycrystalline silicon seed layers

In this work, we present data from solar cells with Si grown by plasma-enhanced chemical vapour deposition as the absorber aterial prepared on polycrystalline silicon seed layers. For the seed layer preparation, the reverse aluminum-induced layer exchange (R-ALILE) process is used. In contrast to the conventional ALILE process, the R-ALILE results in a smooth top surface of the polycrystalline silicon and to the automatic formation of an Al-back contact, which both are beneficial for solar cell preparation. We found that the proper treatment of the seed layers prior to the absorber layer deposition is crucial for a good solar cell performance. Here, we investigated different wet chemical methods (HF-solution, Aletch) and the influence of an H2-plasma treatment. Furthermore, we studied the influence of an additional Ag/indium tin oxide (ITO)-back contact on the solar cell performance. We find that solar cell efficiencies over 5% can be obtained using the presented seed layer concept. The results obtained in this work can help to improve the epitaxial overgrowth of seed layers.