Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 48: Poster 2

HL 48.86: Poster

Donnerstag, 26. März 2009, 15:00–17:30, P2

Lateral Inhomogeneities and Potential Fluctuations in Chalcopyrite Thin-Films and Solar Cells — •Thomas Unold, Markus Wendt, Christina Manclus, Raquel Caballero, Christian Kaufmann, and Hans-Werner Schock — Helmholtz-Zentrum Berlin für Materialien und Energie Gmbh, Berlin, Germany

Polycrystalline chalcopyrite-type semiconductors such as Cu(In,Ga)Se2 show great potential for use in photovoltaic devices with 20% solar conversion efficiency demonstrated for small area thin film devices. These devices exhibit micrometer grain sizes which are of the same order as the film thickness and are found to exhibit significant lateral inhomogenities in their recombination properties. In addition it is found that the highest conversion efficiencies are reached for copper-poor material composition with Cu/III < 0.8, where a large number of defects and compensation is present. We investigate a series of Cu(In,Ga)Se2 thin-film devices with constant gallium content but varying Cu/In+Ga content by temperature-dependent photoluminescence spectroscopy and micro-photoluminencence imaging. We find that the copper-poor samples show much less spatial fluctuations in the recombination properties than the material which is close to stochiometry. The results will be discussed in view of current models of potential fluctuations in chalcopyrite-type thin films.