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DS: Fachverband Dünne Schichten
DS 12: Focused Session: Inhomogeneous Materials for Solar Cells II
DS 12.3: Talk
Monday, March 20, 2017, 16:00–16:15, CHE 89
Investigation of Carrier Transport in CuInGaSe2 by Highly Spatially, Spectrally, and Time Resolved Cathodoluminescence Microscopy — •Mathias Müller1, Martin Müller1, Torsten Hölscher2, Setareh Zahedi-Azad2, 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 inhomegeneities, highly spatially, spectrally, and time resolved cathodoluminescence (CL) measurements have been performed on polycrystalline CuInGaSe2 (CIGSe). Absorbers with varying Cu/III-ratios (CGI: 0.73 and 0.86) and therefore varying grades of disorder were investigated.
For this purpose two separate experiments were combined. Carrier diffusion length was derived temperature dependent from spatially resolved CL measurements as was the initial carrier lifetime from time resolved CL experiments.
With decreasing temperature from 300 K to 4.5 K the diffusion length increases from 6 µm to 27 µm (CGI 0.86) and 23 µm (CGI 0.73). Simultaneously, carrier lifetime increases from 20 ns (@ 125 K) to 48 ns (@ 4.5 K) and from 3 ns (@ 125 K) to 37 ns (@ 4.5 K), respectively. The resulting mobilities follow a power law with µ ∝ T−0.86 (CGI 0.86) and µ ∝ T−0.43 (CGI 0.73), which reveals scattering at neutral defects as the dominant mechanism, reaching up to 340,000 cm2/Vs at 4.5 K.