Berlin 2012 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 5: Thin film photovoltaics: CIGSe + CdTe
DS 5.1: Vortrag
Montag, 26. März 2012, 10:00–10:15, H 2032
Diffusion of Zn in solar-grade Cu(In,Ga)Se2 and single-crystal CuInSe2 thin films — Jens Bastek1, Roland Würz2, Jürgen Albert3, Sascha Sadewasser3, and •Nico Stolwijk1 — 1Universität Münster, Institut für Materialphysik, 48149 Münster — 2Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg, 70565 Stuttgart — 3Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin
The diffusion behaviour of Zn in polycrystalline CIGSe is found to be very similar to that in monocrystalline CISe, which indicates that grain boundaries only play a minor role as segregation sites and fast-transport pathways. The Zn diffusion coefficient shows a slightly stronger temperature dependence than Cd in CIGSe while its values are lower by about one order of magnitude. Surprisingly, the diffusion profiles exhibit peculiar shapes with a second maximum near the CI(G)Se-substrate interface. Zn may be relevant to CIGS technology as it is a major component of the transparent oxide layer. In addition, Zn may penetrate into the active zone during solar-cell processing when the CdS buffer layer is replaced by ZnS. The present results were obtained from diffusion experiments with the radiotracer Zn-65 using lamp-oven annealing followed by ion-beam sputter-sectioning. We will discuss possible implications with regard to diffusion mechanisms and site occupancy.