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  Caballero, R.; Kaufmann, C.A.; Rissom, T.; Efimova, V.; Hoffmann, V.; Schock, H.W.: CIGSe multi-stage co-evaporation: Evolution of Na distribution and thin film morphology. In: 21st International Photovoltaic Science and Engineering Confernce November 28th - December 2nd, 2011, Fukuoka, Japan, 2011, p. [1-2]

Abstract:
Cu-rich growth and/or the possible presence of a Cu-deficient vacancy compound in the front interface near region are often argued to have significant impact on the quality of Cu(In,Ga)Se2 (CIGSe) thin films used as absorber layers in thin film solar cell devices. Also, Na is known to improve the electronic properties of CIGSe thin films with a further affect on the resulting device. This work looks at the correlation of the Cu- and Na-contents in CIGSe thin films during multi-stage co-evaporation and the effect on the resulting device performance. As a result it is shown that grain growth can occur prior to achieving a Cu-rich overall composition and that Na has a strong affinity for Cu-deficient phases within the deposited thin film.