Dresden 2009 – scientific programme
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DS: Fachverband Dünne Schichten
DS 26: Poster II
DS 26.60: Poster
Wednesday, March 25, 2009, 09:30–12:30, P5
Properties of hydrogenated amorphous silicon thin film solar cells deposited at high base pressure — •Jan Woerdenweber1, Tsvetelina Merdzhanova1,2, Aad Gordijn1, Wolfhard Beyer1,2, Helmut Stiebig2, and Uwe Rau1 — 1Forschungszentrum Juelich, Germany — 2Malibu GmbH & Co. KG, Bielefeld, Germany
In thin film silicon solar cell technology, the base pressure of the process appears as an important cost factor. The intention of this study is to investigate to what degree deposition conditions like total process gas flow and deposition rate allow the preparation of solar cells with high stable efficiencies at high base pressures (up to 10−4 Torr). Series of solar cells with various oxygen contaminations were prepared using an intentional oxygen leak. A high total gas flow and high deposition rate (via high RF power) are found to favor the suppression of oxygen incorporation. Thus, the tolerated oxygen flow can be increased by two orders of magnitude. The increase in deposition rate (from ≈ 0.2 nm/s to ≈ 0.5 nm/s) reduces the oxygen incorporation in the intrinsic absorber layer only for low total gas flows (e.g., by a factor of 10 at 10−5 Torr). At high total gas flows no significant change of the incorporation probability with increasing deposition rate is observed. Degradation losses (1000 h of light-soaking at 100 W/cm2 irradiation and at 50∘C) in efficiency for uncontaminated cells are ≈ 18