Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 56: Photovoltaik I

HL 56.4: Vortrag

Dienstag, 8. März 2005, 15:45–16:00, TU P-N202

Local inhomogeneities of the quality of the photo excited state and of material composition in Cu(In,Ga)Se₂-absorbers in the few micrometer scale by sub-micron resolved photoluminescence — •Levent Gütay, Rudolf Brüggemann, and Gottfried Heinrich Bauer — Institute of Physics, Carl von Ossietzky University Oldenburg, Germany

We have recorded spectrally resolved photoluminescence from Cu(In,Ga)Se₂ absorbers (Ga content of 29% and 46%) deposited on Mo coated substrates and overcoated by a 50 nm thick CdS layer. The absorber quality corresponds to pilot line thin film solar cell production with module efficiencies of 12-14 %. We translate the lateral variation of the luminescence yield into the splitting of the quasi Fermi levels, say laterally varying open circuit voltages. Further we discuss the laterally varying low energy wing of PL-spectra, reflecting variations of optical threshold energies for absorption/emission (band gap) of about 15 meV, in terms of variations in material composition, such as Ga-content. The comparison of XPS-analyses with high lateral resolution fits qualitatively to this explanation.