Dresden 2011 – scientific programme
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DS: Fachverband Dünne Schichten
DS 6: Thin Film Chalcogenide Photovoltaics III (Focused Session -- Organiser: Ronning)
DS 6.4: Talk
Monday, March 14, 2011, 16:45–17:00, GER 37
Influence of band-gap grading on luminescence properties of Cu(In,Ga)Se2 — •Jakob Haarstrich1, Heiner Metzner1, Carsten Ronning1, Thorsten Rissom2, Christian A. Kaufmann2, Hans-Werner Schock2, and Andreas Undisz3 — 1Institut für Festkörperphysik, Friedrich Schiller Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany — 2Helmholtz-Zentrum Berlin für Materialien und Energie, Solar Energy Research, Institute for Technology, Lise-Meitner-Campus, Hahn-Meitner-Platz 1, 14109 Berlin, Germany — 3Institute for Material Science and Technology, Metallic Materials, Friedrich-Schiller-University Jena, Loebdergraben 32, 07743 Jena, Germany
Cathodoluminescence (CL) has been measured on Cu(In,Ga)Se2 with Ga-grading as it is used in high-efficiency thin-film solar cells at 10 K in both cross-section and plain view configuration. In cross-section geometry, we show that the vertical profile of the emission energy represents the Ga-profile in the film and, thus, we are able to measure the band-gap grading present by means of CL methods. At the same time, we observe a strong drift of excited charge carriers towards the minimum of the band-gap which can be explained by the Ga-grading. It is shown by voltage-dependent CL, how these results directly influence the interpretation of luminescence spectra obtained on Ga-graded Cu(In,Ga)Se2 and, thus, they will have to be considered as a basis for all forthcoming investigations on this topic.