Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 50: Poster II
HL 50.99: Poster
Donnerstag, 30. März 2006, 16:30–19:00, P3
Study of bulk defects in CuIn1−xGaxSe2 based solar cells — •Verena Mertens1, Jürgen Parisi1, Robert Kniese2, Marc Köntges3, and Rolf Reineke-Koch3 — 1University of Oldenburg , Institute of Physics, Energy and Semiconductor Research Laboratory, 26111 Oldenburg — 2Center for Solar Energy and Hydrogen Research (ZSW), Heßbrühlstr. 21c, 70565 Stuttgart — 3Institut für Solarenergieforschung Hameln/Emmerthal (ISFH), Am Ohrberg 1, 31860 Emmerthal
CuIn1−xGaxSe2 based solar cells with different molar gallium to gallium plus indium ratio (GGI) are investigated concerning the bulk defects of the absorber material using admittance spectroscopy (AS) and deep level transient spectroscopy (DLTS). The study aims to clarify why in devices with GGI larger than 0.3 the open circuit voltage does not increase linearly with the band gap of the material as it does in those with gallium poor absorber layers. We find that in samples with mixed absorber composition, i.e. those containing both indium and gallium, the same bulk defects are detected. The devices with CuInSe2 and CuGaSe2 absorbers show some additional trap signals. As no principle difference in defect spectra of gallium poor and gallium rich samples is found, we conclude that the bulk defects of the absorber material do not play an important role concerning the ”open circuit voltage problem“ of the gallium rich devices.