Regensburg 2013 – scientific programme
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DS: Fachverband Dünne Schichten
DS 32: Poster Session IV: Atomic layer deposition; Organic thin films; Organic Electronics and Phototovoltaics; Organic Materials for Spintronics - from spinterface to devices; Thin film photovoltaic materials and solar cells
DS 32.59: Poster
Thursday, March 14, 2013, 17:00–20:00, Poster B2
Composition-dependent atomic-scale structure of Cu(In,Ga)S2 — •Stefanie Eckner1, Helena Kämmer1, Tobias Steinbach1, Martin Gnauck1, Andreas Johannes1, Christiane Stephan2, Susan Schorr2, and Claudia Sarah Schnohr1 — 1Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany — 2Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
In order to exploit the full potential of Cu(In,Ga)S2-based thin film solar cells, a deeper understanding of the composition-dependent atomic-scale structure along with its influence on electrical properties such as the band gap is necessary. In this study, element-specific first nearest neighbour distances of Cu(In,Ga)S2 were determined as a function of the In/(In+Ga) ratio using extended X-ray absorption fine structure spectroscopy. All three bond lengths, namely Cu-S, Ga-S and In-S, are found to differ from each other and to remain nearly constant over the whole compositional range of 0 ≤ In/(In+Ga) ≤ 1 despite the significant change of the lattice constants. Structural parameters have also been simulated with a valence force field model for all possible first nearest neighbour configurations surrounding the S anions. Excellent agreement between the calculated average bond lengths and the experimental values is obtained for a non-random distribution of In and Ga atoms that favours a mixed Cu-In-Ga configuration over the pure Cu-In or Cu-Ga first nearest neighbour shells.