Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 38: Photovoltaics: CIGS and related Materials
HL 38.2: Vortrag
Dienstag, 27. März 2012, 11:30–11:45, ER 270
Correlation of surface contour, optoelectronic and spectroscopic properties of Cu(In,Ga)Se2 by SNOM and AFM — •Oliver Neumann1, Stephan J. Heise1, Rudolf Brüggemann1, Max Meessen1, Wolfram Witte2, Dimitrios Hariskos2, and Gottfried H. Bauer1 — 1Institute of Physics, Carl von Ossietzky University Oldenburg, Germany — 2Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), Stuttgart, Germany
Chalcopyrite absorbers exhibit local fluctuations of structural, optical and optoelectronic properties. We study the correlation of the surface contour and the local properties such as the integrated photoluminescence (PL) yield and the splitting of the quasi-Fermi levels in a Cu(In,Ga)Se2-based thin-film system at room temperature by AFM and spatially resolved PL measurements at the identical position with a scanning near-field optical microscope (SNOM). The Cu(In,Ga)Se2 layer is deposited on glass, etched with bromine-methanol to smooth the surface for a more homogeneous incoupling of laser light, and passivated with cadmium sulfide. Our measurements reveal a high structural correlation between surface contour, integrated PL yield and quasi-Fermi level splitting. Additionally, we observe trenches in the surface contour which correspond to a dip or to a peak in the splitting of the quasi-Fermi levels and integrated PL yield. Furhermore some trenches show spectral variation of the PL compared to their direct environment. We discuss these observations with respect to the optoelectronic property and the composition of the absorber.