Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Poster 1

HL 13.68: Poster

Monday, March 26, 2007, 15:00–17:30, Poster A

Identification and Quantification of Local Absorber Properties of Cu(In,Ga)Se2 from Sub-Micron Resolved PL and Optical Transmission — •Levent Gütay and Gottfried Bauer — Institute for Physics, University of Oldenburg, 26111 Oldenburg, Germany

We have analyzed Cu(In,Ga)Se2 absorber layers with a confocal microscope setup designed for photoluminescence (PL) and optical transmission experiments with lateral resolution in the 1-micron scale and below. We present results for inhomogeneities of optoelectronic properties of Cu(In1-xGax)Se2-absorbers in terms of fluctuations of the local band gap and of splitting of quasi-Fermi-levels which can be extracted from spectrally resolved PL data. From optical transmission spectra we get additional data for local band gaps and their fluctuations. The optical threshold for photon absorption/emission in Cu(In1-xGax)Se2 is a complicated function of wavelength/photon energy that cannot be reduced to a single parameter band gap, we plot photon energies for different degrees of absorption (e.g. α = 10^n 1/cm, with n = 2,3,4) as pseudo-band gap energy. We summarize fluctuations in Fermi level splitting and optical pseudo band gap energies in histograms and discuss their local interdependence in terms of correlation factors.