Degradation mechanism(s) of GaAs solar cells with Cu contacts

Substrate-based GaAs solar cells having a dense Au/Cu front contact grid with 45% surface coverage were exposed to accelerated life testing at temperatures between 200 and 300 C. TEM analysis of the front contacts was used to gain a better understanding of the degradation process. During accelerated...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2016-04, Vol.18 (15), p.1232-124
Main Authors: van Leest, R. H, de Kleijne, K, Bauhuis, G. J, Mulder, P, Cheun, H, Lee, H, Yoon, W, van der Heijden, R, Bongers, E, Vlieg, E, Schermer, J. J
Format: Article
Language:English
Subjects:
Accelerated life tests
Contact
Degradation
Gallium arsenide
Photovoltaic cells
Recrystallization
Solar cells
Ultrasonic testing
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Summary:Substrate-based GaAs solar cells having a dense Au/Cu front contact grid with 45% surface coverage were exposed to accelerated life testing at temperatures between 200 and 300 C. TEM analysis of the front contacts was used to gain a better understanding of the degradation process. During accelerated life testing at 200 C only intermixing of the Au and Cu in the front contact occurs, without any significant influence on the J V curve of the cells, even after 1320 h (55 days) of accelerated life testing. At temperatures 250 C a recrystallization process occurs in which the metals of the contact and the GaAs front contact layer interact. Once the grainy recrystallized layer starts to approach the window, diffusion via grain boundaries to the window and into the active region of the solar cells occurs, causing a decrease in V oc due to enhanced non-radiative recombination via Cu trap levels introduced in the active region of the solar cell. To be a valid simulation of space conditions the accelerated life testing temperature should be
ISSN:1463-9076
1463-9084
DOI:10.1039/c6cp01428c