Aluminum Alloying in Local Contact Areas on Dielectrically Passivated Rear Surfaces of Silicon Solar Cells

We present a detailed study on the rear contact formation of rear-surface-passivated silicon solar cells by full-area screen printing and alloying of aluminum pastes on the locally opened passivation layer. We demonstrate that applying conventional Al pastes exhibits two main problems: (1) high cont...

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Bibliographic Details
Published in:IEEE electron device letters 2011-07, Vol.32 (7), p.916-918
Main Authors: Rauer, M., Woehl, R., Ruhle, K., Schmiga, C., Hermle, M., Horteis, M., Biro, D.
Format: Article
Language:English
Subjects:
Alloying
Aluminum
Aluminum alloying
Aluminum base alloys
Aluminum oxide
Applied sciences
Contact
Electronics
Energy
Exact sciences and technology
local back surface field
local emitter
Natural energy
Optoelectronic devices
Passivation
Pastes
Photovoltaic cells
Photovoltaic conversion
Printing
Screen printing
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Silicon
silicon solar cells
Solar cells
Solar cells. Photoelectrochemical cells
Solar energy
Surface emitting lasers
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Summary:We present a detailed study on the rear contact formation of rear-surface-passivated silicon solar cells by full-area screen printing and alloying of aluminum pastes on the locally opened passivation layer. We demonstrate that applying conventional Al pastes exhibits two main problems: (1) high contact depths leading to an enlargement of the contact area and (2) low thicknesses of the Al-doped p + Si regions in the contact points resulting in poor electron shielding. We show that this inadequate contact formation can be directly linked to the deficiently low percentage of silicon that dissolves into the Al-Si melt during alloying. Thus, by intentionally adding silicon to the Al paste, we could significantly improve the contact geometry by reducing the contact depth and enlarging the Al-p + thickness in the contact points, enabling a simple industrially feasible way for the rear contact formation of silicon solar cells.
ISSN:0741-3106
1558-0563
DOI:10.1109/LED.2011.2143385