Berlin 2008 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 12: Photovoltaic
HL 12.4: Talk
Monday, February 25, 2008, 14:45–15:00, EW 202
Deposition and characterization of (Zn,Mg)O buffer layers on CIGSSe thin film solar cells — •Benjamin Hußmann1, Felix Erfurth1, Thomas Niesen2, Jörg Palm2, Alexander Grimm3, Achim Schöll1, and Eberhard Umbach1,4 — 1Universität Würzburg, Experimentelle Physik II — 2Avancis GmbH, München — 3Hahn-Meitner-Institut, Berlin — 4Forschungszentrum Karlsruhe
(Zn, Mg)O buffer layers on Cu(In,Ga)(S,Se)2 (CIGSSe) thin film solar cells are promising alternatives to CdS buffer layers by featuring comparable efficiencies, better environmental compatibility and the possibility to implement the deposition process into a vacuum processing line. The (Zn, Mg)O buffer layers are deposited by radio frequency magnetron co-sputtering from two separate ZnO and MgO ceramic sputter targets to control the Mg-content and therefore the band gap of the buffer layer. In our experimental setup the sputter preparation chamber is connected with a UHV analysis system which allows in-situ characterization with X-ray photoelectron spectroscopy (XPS). The interface between the absorber and the buffer layer is believed to have a major influence on the cell efficiency and is thus of particular interest in this work. This interface has been investigated during layer deposition by sequentially interrupting the sputter process and performing XPS scans. We observed island growth of (Zn,Mg)O on CIGSSe and a strong oxidation of the absorber surface induced by the deposit. In order to complement the chemical and electronic information with structural data, energy dispersive X-ray analysis, X-ray diffraction, and scanning electron microscopy have been applied.