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Proceedings Paper

Lowest surface recombination velocity on n-type crystalline silicon using PECVD a-Si:H/SiNx bi-layer passivation
Author(s): Dmitri S. Stepanov; Zahidur R. Chowdhury; Nazir P. Kherani
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Paper Abstract

Energy conversion efficiency of crystalline silicon (c-Si) solar cells manufactured on thin substrates is strongly influenced by the recombination losses of photo-generated charge carriers at the surface and in its proximity. Intrinsic hydrogenated amorphous silicon (i-a-Si:H) deposited using DC saddle-field plasma enhanced chemical vapour deposition (PECVD) at a low temperature of ~200°C reduces recombination losses of photo-generated carriers through passivation of defects at the surface. This study reports on high quality surface passivation achieved using a dual layer approach wherein a 70nm amorphous silicon nitride (SiNx) capping layer is deposited on a less than 10nm thin i-a-Si:H layer. While the a-Si:H layer is effective in passivating the interface recombination sites, SiNx is deemed to incorporate field-effect passivation, thus providing a minority carrier mirror. Additionally, SiNx layer acts as an anti-reflection coating with a low absorption coefficient in the optical frequency range of interest. The SiNx deposition conditions, known to strongly influence the passivating quality of the dual layer structure, were systematically investigated using the response surface methodology (RSM). The optimal deposition parameters obtained from the RSM study were experimentally verified to yield the lowest surface recombination velocity of 3.5 cm/s on 1-2 Ω-cm n-type FZ c-Si using a PECVD a-Si:H/SiNx bi-layer passivation stack.

Paper Details

Date Published: 8 September 2011
PDF: 6 pages
Proc. SPIE 8007, Photonics North 2011, 800720 (8 September 2011); doi: 10.1117/12.905624
Show Author Affiliations
Dmitri S. Stepanov, Univ. of Toronto (Canada)
Zahidur R. Chowdhury, Univ. of Toronto (Canada)
Nazir P. Kherani, Univ. of Toronto (Canada)

Published in SPIE Proceedings Vol. 8007:
Photonics North 2011
Raman Kashyap; Michel Têtu; Rafael N. Kleiman, Editor(s)

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