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HL: Fachverband Halbleiterphysik
HL 24: Poster Session: Ge/Si/SiC / III - V Semiconductors
HL 24.21: Poster
Montag, 26. März 2012, 16:00–19:00, Poster D
Measurement of the dependency of the defect density on the band gap in a-SiGe:H thin films — •Burkhard Gilles1, Ulrich Heinzmann1, Helmut Stiebig2, Andreas Gondorf2, Pavel Prunici2, and Florian Maier2 — 1Molecular and Surface Physics, Bielefeld University, 33615 Bielefeld, Germany — 2Malibu GmbH Co. KG, 33609 Bielefeld, Germany
Increasing the quality of the amorphous silicon [aSi] and Silicon-Germanium alloys [aSiGe] is a necessary task for solar energy conversion efficiency of thin film solar cells. The defect states of a-Si:H based materials - represented by the dangling bond density and the Urbach tail - depend on the applied deposition conditions and the composition of the layer. A deeper understanding of the defect state distribtion is a crucial requirement to further enhance the efficiency and the long term stability of thin film silicon based solar cells. The dependency of the defect density on the Fermi energy was already subject of many investigations. In this work, the dependency of the defect density on the band gap will be investigated. In order to determine the defect distribution a constant photocurrent measurement (CPM) setup was installed. CPM spectra from a-SiGe:H layers will be presented. The quality of the material and the dependency of the defect density on the band gap will be discussed.