Berlin 2015 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
DS: Fachverband Dünne Schichten
DS 2: Thin Film Characterisation I: Structure Analysis and Composition
DS 2.4: Vortrag
Montag, 16. März 2015, 10:15–10:30, H 0111
Atom probe tomography study of the p-n junction in CIGS thin-film solar cells — •Anna Koprek1, Oana Cojocaru-Mirédin1, Christoph Freysoldt1, Roland Wuerz2, and Dierk Raabe1 — 1Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, 40237 Düsseldorf, Germany. — 2Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg, Industriestrasse 6, 70565 Stuttgart, Germany.
Solar cells based on Cu(In,Ga)Se2 (CIGS) are one of the most promising among thin film technology. Despite high efficiency over 20%, the cells are still far below the theoretical limit of ∼ 30%. Recent studies indicate that the Cd, S, and Cu that interdiffuse across the p-n junction strongly affect the electrical properties of the device.
In this work atomic scale investigation combined with electrical measurements is presented for CdS/CIGS interfaces of CIGS solar cells annealed at different temperatures. The electrical characterization shows decrease of efficiency of the cells with increasing temperature of annealing. By means of atom probe tomography Cd and S diffusion is traced. Indeed, after annealing, besides the Cu-depleted and Cd-enriched CIGS surface, Cd had diffused over a long distance into the absorber. This is contrasted with an as-grown sample for which Cd-enriched and Cu,Ga-depleted zones were observed only at the CIGS surface. The Cd2+ ions are expected to occupy Cu rather than Ga sites as Cd2+ and Cu+ have similar ionic radii. Such CdCu+ donors could change the p-n junction properties as it was suggested by “Buried homojunction” and “Type inversion of the CIGS surface region” models.