Berlin 2018 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 18: Optical Analysis of Thin Films (Reflection, Ellipsometry, Raman, IR-DUV Spectroscopy, ...): Session I
DS 18.10: Vortrag
Mittwoch, 14. März 2018, 12:30–12:45, H 0111
Two-Dimensional Optical Transport Measurements in CuInGaSe2 by Highly Spatially, Spectrally, and Time Resolved Cathodoluminescence Microscopy — •Mathias Müller1, Torsten Hölscher2, Matthias Maiberg2, Frank Bertram1, Roland Scheer2, and Jürgen Christen1 — 1Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — 2FG Photovoltaik, Martin-Luther-University Halle-Wittenberg, Germany
To gain a deeper understanding regarding transport of carriers and the influence of inhomegenieties, highly spatially, spectrally, and time resolved cathodoluminescence (CL) measurements have been performed on polycrystalline CuInGaSe2 (CIGSe) with varying Cu/III-ratios (CGI: 0.8 and 0.87). For this purpose, one-dimensional and two-dimensional optical transport measurements are compared, and performed to determine lateral carrier diffusion lengths. The samples are etched with bromine-methanol to smoothen the surface for further processing. 220 nm thick Ti masks of different shapes are applied via photolithography. One-dimensional measurements are carried out in CL-linescans perpendicular to the mask’s edge. In a second step for the two-dimensional measurements, the sample is excited by the pulsed e-beam in the center of circular apertures in the Ti-mask with diameters ranging from 2.5 µm to 50 µm. Both methods lead to concurrent low temperature (T = 5 K) diffusion lengths of ca. 20 µm. Furthermore, a strong spatial dependence of the carrier lifetime is revealed with lifetimes ranging from 17 ns to 50 ns over only a few µm.