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Proceedings Paper

Textured, doped, ZnO thin films produced by a new process for a-Si and CIGS solar cell application
Author(s): S. Y. Guo; L. Sahoo; G. Sosale; A. E. Delahoy
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Paper Abstract

The properties of a transparent conductive oxide (TCO) used as a front electrode for thin-film solar cells and modules play a major role in determining the maximum attainable conversion efficiency. Doped ZnO is an important TCO that is widely used in amorphous/nanocrystalline silicon (a-Si/nc-Si) and CIGS thin-film solar cells. In the case of a-Si/nc-Si cells, the ZnO thin film should be textured to promote light trapping to increase the short-circuit current density Jsc. In this work, textured, aluminum-doped ZnO (ZnO:Al) thin films have been directly deposited by a sputtering-based method and without the need for post-deposition etching. The morphology, optical properties and electrical properties of the films have been studied. SEM micrographs show that feature sizes around 0.2 - 0.4μm have been achieved at a film thickness of 1μm, and that the morphology can be controlled by the deposition conditions. AFM images were analyzed to extract a set of topographic parameters (amplitude, spatial, and hybrid). The optical transmission, haze, and angle-resolved light scattering of the textured ZnO:Al films were measured and compared to properties of commercially-available textured SnO2:F thin films on glass. Higher haze and reduced absorption could be obtained with the textured ZnO:Al films. Hall effect measurements on these films yielded a carrier concentration and mobility of 2.75 x 1020cm-3 and 24.1cm2/Vs, respectively. We also report that the use of these textured ZnO:Al films as the top TCO for CIGS solar cells results in reduced cell reflectance and increased Jsc. The novel deposition method provides a potential pathway to large area and cost effective production of a textured ZnO TCO for thin-film PV manufacturing operations.

Paper Details

Date Published: 11 September 2007
PDF: 10 pages
Proc. SPIE 6651, Photovoltaic Cell and Module Technologies, 66510B (11 September 2007); doi: 10.1117/12.736084
Show Author Affiliations
S. Y. Guo, Energy Photovoltaics, Inc. (United States)
L. Sahoo, Energy Photovoltaics, Inc. (United States)
G. Sosale, McGill Univ. (Canada)
A. E. Delahoy, Energy Photovoltaics, Inc. (United States)

Published in SPIE Proceedings Vol. 6651:
Photovoltaic Cell and Module Technologies
Bolko von Roedern; Alan E. Delahoy, Editor(s)

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