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Microstructure and Optical Functions of Transparent Conductors and their Impact on Collection in Amorphous Silicon Solar Cells

Published online by Cambridge University Press:  01 February 2011

G. M. Ferreira
Affiliation:
Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea.
ChiChen A.
Affiliation:
Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea.
S. Ferlauto
Affiliation:
Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea.
P. I. Rovira
Affiliation:
Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea.
Ilsin An
Affiliation:
Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea.
C.R. Wronski
Affiliation:
Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea.
R. W. Collins
Affiliation:
Materials Research Institute, Center for Thin Film Devices, and Department of Physics, The Pennsylvania State University, University Park, PA 16802
G. Ganguly
Affiliation:
Materials Research Institute, Center for Thin Film Devices, and Department of Physics, The Pennsylvania State University, University Park, PA 16802
Joong Hwan Kwak
Affiliation:
BP Solar, 3601 LaGrange Parkway, Toano VA 23168;
Koeng Su Lim
Affiliation:
BP Solar, 3601 LaGrange Parkway, Toano VA 23168;
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Abstract

We have developed new procedures for determining the microstructure as well as the index of refraction and extinction coefficient spectra {n(E), k(E)} for textured SnO2 thin films on glass used as the top contact layers and superstrate for amorphous silicon (a-Si:H) p-i-n solar cells. These procedures combine (i) multichannel Mueller matrix spectroscopy using a dual rotating-compensator spectroscopic ellipsometer in reflection from the surface of the SnO2, a measurement that is most sensitive to microstructure and n(E), and (ii) transmission spectroscopy through a double-thick SnO2 sandwich contacted with index-matching fluid, a measurement that is most sensitive to k(E). An important optical loss in a-Si:H p-i-n solar cells is reflection from the SnO2/p-layer interface. In this paper, we characterize this optical loss through modeling the solar cell optical quantum efficiency and demonstrate the extent to which microscopic roughness at this interface can serve as an anti-reflection layer for enhanced collection.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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