Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 30: Photovoltaik II
HL 30.2: Vortrag
Mittwoch, 10. März 2004, 15:30–15:45, H14
Influence of Film Texture on Grain Boundary Activity in Cu(In,Ga)Se2 Films — •G. Hanna1, N. Ott2, H.P. Strunk2, T. Glatzel3, S. Sadewasser3, U. Rau1, and J.H. Werner1 — 1Institut für Physikalische Elektronik, Universität Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart — 2Institut für Werkstoffwissenschaften VII, Universität Erlangen Nürnberg — 3Hahn Meitner Institut, Berlin
A preferred (220/204) crystallographic orientation (texture) of Cu(In,Ga)Se2 (CIGS) absorber layers is beneficial for the performance of finished CIGS solar cells as compared to (112) textured CIGS layers [1,2]. We study the laterally resolved electronic properties of CIGS thin films with different textures by means of Cathodoluminescence (CL) mapping, measured in a transmission electron microscope, and Kelvin Probe Force Microscopy (KPFM). The (220/204) textured samples have a very homogenous lateral CL-intensity whereas the (112) textured samples exhibit strong contrasts in the CL-signal. The line scans of the work function Φ across grain boundaries (GBs) measured with KPFM exhibit a dip of more than 300 meV across the GB at a (112)-textured sample while a (220/204) sample shows no comparable dip of Φ at the GB but rather small spikes. Both measurement methods show that the superior properties of CIGS solar cells with (220/204)-textured absorbers as compared to (112)-textured absorbers are due to a lower electronic activity of the film’s GBs resulting in a lower recombination of minority carriers at the GBs.
[1] M. A. Contreras et al., Prog. Photovolt. Res. Appl. 7 311 (1999).
[2] S. Chaisitsak et al., Jpn. J. Appl. Phys. 41 507 (2002).