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Mesa Separation of GaInP Solar Cells by Picosecond Laser Ablation

: Weber, J.; Klinger, V.; Brand, A.; Gutscher, S.; Wekkeli, A.; Mondon, A.; Oliva, E.; Dimroth, F.


IEEE Journal of Photovoltaics 7 (2017), No.1, pp.335-339
ISSN: 2156-3381
Journal Article
Fraunhofer ISE ()
Materialien - Solarzellen und Technologie; Photovoltaik; III-V und Konzentrator-Photovoltaik; III-V Epitaxie und Solarzellen; III-V semiconductors; laser ablation threshold; separation of III-V solar cells; mesa

Laser ablation processes provide a potentially low cost and fast technology for microstructuring semiconductors, metals, or dielectrics. This paper deals with picosecond laser ablation (λ = 532 nm, τ ≈ 9 ps) of III-V semiconductors. In particular, the external threshold fluence of thermal ablation is determined for InP, GaAs, and GaP. Furthermore, the applicability of laser ablation to the electrical separation of III-V solar cells is discussed. In this context, current-voltage characteristics are presented comparing GaInP single-junction solar cells separated by picosecond laser ablation and wet-chemical mesa etching. The laser process leads to a significant drop in open-circuit voltage and fill factor which is explained by a more than three times larger (unpassivated) surface area.