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LBIC Investigations of multicrystalline silicon solar Cells with the front contact on grain boundaries
V. Schlosser1, R. Ebner2, J. Summhammer2, P. Bajons1, G. Klinger3
1Institut
für Materialphysik, Fakultät für Physik, Universität
Wien, Strudlhofg 4, A-1090 Wien, Austria,
email: viktor.schlosser
@univie.ac.at
2Vienna University of Technology, Atominstitut, Stadionallee 2, A-1020 Wien, Austria, email: summhammer@ati.ac.at
3Institut für Meteorologie und Geophysik, Universität Wien, Althanstr.14, A-1090 Wien, Austria, email: img-wien@univie.ac.at
ABSTRACT: The spatial variation of locally generated photocurrents has been mapped for multi crystalline silicon solar cells equipped with two different kind of front metal grids. To a portion of the 100 mm x 100 mm solar cells the standard H-pattern with straight metal lines and two busbars was applied. The other cells were equipped with a front grid located on grain boundaries. The light beam induced current (LBIC) set-up works with two fibre coupled luminescence diodes at centre wavelengths of 655 nm and 870 nm respectively. The two light emitting diodes (LEDs) were driven by the same current and individually intensity modulated. A feedback loop for the LED current maintained a constant photocurrent arising from the red LED. The cell current caused by the infrared LED was recorded as a function of the light spot position on the solar cell. The solar cells were investigated under different electrical bias conditions using a low intensity white light background illumination of the whole cell. With the experimental set-up we were able to separate electrical and optical inhomogenities of the surface from the local electrical bulk properties.
Keywords: Multi-Crystalline, Silicon, LBIC
