ABSTRACT: Thin film microcrystalline silicon (¿c-Si:H) solar cell is an attractive material because of its extended response in the long wavelength region. It suffers less from degradation on prolonged exposure to light when compared with amorphous silicon. Based on these features, ¿c-Si:H solar cells are implemented as bottom cell the so-called micromorph tandem cells for enhanced light absorption resulting in a higher conversion efficiency. This contribution investigates the effect of seeding the growth of ¿c-Si:H deposited by radio frequency plasma enhanced chemical vapour deposition (rf PECVD) on the spectral response of ¿c-Si:H solar cells. We correlate the crystalline volume fraction of the absorber layer to the silane concentration used during the deposition and thickness of the seed layer. Our results show that with seeding of both the p- and i-layers, the overall solar-cell performance increases mainly due to extended spectral response of the solar cell in the long wavelength region of the solar spectrum. The Jsc is increased from 173 A/m2 to 239 A/m2. On the other hand, the Voc and fill factor drop by 11% and 2.9%, respectively. By means of bifacial Raman measurement, we demonstrate that the seed layers help to reduce the amorphous incubation layer and lead to a more rapid crystallinity development in growth direction. We show that the crystallinity profile in the growth direction is more uniform when compared with a ¿c-Si:H layer deposited without seeding.
Keywords: Thin film microcrystalline silicon, seed layers, crystallinity, spectral response
|Title of host publication||Proceedings of the 25th European Photovoltaic Solar Energy Conference and Exhibition|
|Place of Publication||Valencia|
|Number of pages||4|
|Publication status||Published - 2010|
- conference contrib. refereed
- Conf.proc. > 3 pag