Berlin 2008 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 17: Poster I
HL 17.29: Poster
Monday, February 25, 2008, 16:30–19:00, Poster D
Local Fluctuations of Absorber Properties of Cu(In,Ga)Se2 for ”Real Life” Conditions by Sub-Micron Resolved PL — •Levent Gütay and Gottfried H. Bauer — Institute of Physics, University of Oldenburg, Germany
We analyze Cu(In,Ga)Se2 absorber layers and solar cells in a confocal microscope setup by photoluminescence (PL) experiments. We present results on lateral inhomogeneities of the absorbers in terms of local fluctuations of the band gap and splitting of quasi-Fermi-levels which can be extracted from spectrally resolved PL (300K) scans across several tens of microns. Excitation fluxes amount to 102 −105 suns equivalent. We analyze the significance and the statistical distribution of the occurring fluctuations of splitting of quasi-Fermi-levels (EFn−EFp) which we plot in histograms, seemingly showing gaussian-like shapes. The width and shape of these distributions will be discussed, as they show substantial dependence on the excitation flux. We have extrapolated the features of the histograms from our excitation fluxes towards 1 sun equivalent in order to correct our data for absolute values (EFn−EFp) derived from calibrated luminescence analyses at 300 K and 1 sun equivalent on non-laterally resolved PL-studies, which provide access to the average on PL-yields (ln(∑YPL)) instead of the average of local (EFn−EFp) which writes (∑ln(YPL)). In our approach we strongly appeal for sufficient high spatial resolution of any experiment on polycrystalline solid matter.