Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 68: Photovoltaics: Chalcopyrites II
HL 68.6: Talk
Thursday, March 17, 2011, 11:30–11:45, FOE Anorg
Investigations of lateral and vertical compositional gradients in Cu(In,Ga)Se2 by highly spatially, spectrally and time resolved cathodoluminescence spectroscopy — •Mathias Müller1, Stefan Ribbe1, Thomas Hempel1, Frank Bertram1, Wolfram Witte2, Dimitrios Hariskos2, and Jürgen Christen1 — 1Institute for Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — 2Zentrum für Sonnenenergie- und Wasserstoff-Forschung, Baden Württemberg (ZSW), Stuttgart, Germany
Luminescence properties of Cu(In,Ga)Se2 (CIGS) layers with different thicknesses were investigated by means of highly spatially, spectrally and time resolved cathodoluminescence (CL) spectroscopy at low temperature (T = 5 K). A polycrystalline CIGS thin film with a thickness of 2.4 µm was grown using an in-line co-evaporation process with a final Cu-poor composition on top of a sputtered Mo layer on a soda lime glass substrate. The layer thickness was then reduced by highly controlled bromine methanol etching. The typical grainy (daverage = 3 µm) structure of the untouched sample develops thin longish structures under the influence of the etchant. Integral CL spectra of the samples are dominated by donor-acceptor pair (DAP) luminescence. The peak energies of these spectra are ranging from 1.13 eV to 1.22 eV with decreasing layer thickness. The lateral distribution of the luminescence is inhomogeneous regarding the intensity as well as the peak energy. Time resolved CL shows a strong dependence of the initial lifetime from the emission energy.