Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 68: Photovoltaics: Chalcopyrites II
HL 68.11: Vortrag
Donnerstag, 17. März 2011, 13:00–13:15, FOE Anorg
Photoelectric properties of variably RTP processed CIGS2 solar cells — •Julia Riediger1, Jörg Ohland1, Martin Knipper1, Jürgen Parisi1, Ingo Riedel1, Roland Mainz2, Saoussen Merdes2, and Joachim Klaer2 — 1Energy and Semiconductor Research Laboratory, Department of Physics, University of Oldenburg, 26111 Oldenburg, Germany — 2Helmholtz-Zentrum Berlin für Materialien und Energie Berlin GmbH, Glienicker Straße100, 14109 Berlin, Germany
The open circuit voltage Voc of CuInS2 solar cells was found to improve via incorporation of gallium. The Cu(In,Ga)S2 absorber of the samples studied in this work was prepared by sputtering (Cu,Ga) and In precursors subsequently sulfurized via rapid thermal processing (RTP) in sulfur vapor. Distinctive top/bottom CuInS2/CuGaS2 segregation has been observed which extent depends on the substrate temperature and holding time of the temperature during RTP-process. The insufficient gallium accumulation at the surface impedes high values of Voc.We studied the consequences of RTP-process parameter variation in regard of the interdiffusion of CuInS2 and CuGaS2. Quantum efficiency (QE) and temperature-/illumination-dependent current-voltage (IV) profiling have been carried out for differently processed samples. These measurements provide the minimum band gap Eg of the graded absorber layer, the temperature dependent Voc and the activation energy Ea for carrier recombination. Drive level capacitance (DLCP) profiling reveals the spatially resolved in-depth variation of the doping/defect concentration close to the space charge region.