Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 85: Poster Session II
HL 85.62: Poster
Donnerstag, 17. März 2011, 18:00–21:00, P4
Spatially resolved photoluminescence and AFM measurements on Cu(In,Ga)Se2-based thin film absorbers prepared with different throughput speeds — •Max Meessen1, Oliver Neumann1, Stephan J. Heise1, Rudolf Brüggemann1, Wolfram Witte2, Dimitrios Hariskos2, and Gottfried H. Bauer1 — 1Institut für Physik, Carl von Ossietzky Universität Oldenburg, Germany — 2Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), Stuttgart, Germany
We study the behavior and interdependence of quantities such as photoluminescence (PL) yield, quasi-Fermi level splitting and AFM-determined surface roughness on CIGS thin-film absorbers with different thicknesses between 0.25 and 3 µm achieved by varying the throughput speed in an in-line physical vapor deposition (PVD) process. These quantities are studied on the macroscopic as well as on the microscopic scale with a resolution of approximately 1 µm. It is shown that the structural sizes of the inhomogeneities of the absorber layer itself and its lateral photoluminescence properties decrease with decreasing absorber thickness. These results are compared to those on samples thinned by bromine-methanol etching.
Furthermore, we show that varying the thickness of the CdS buffer layer on top of the absorber influences surface recombination and thereby PL yield and quasi-Fermi level splitting. A decrease in surface recombination at higher buffer thicknesses has to be weighed against the increase in absorption in the buffer layer, which in turn decreases carrier generation in the absorber layer.