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Characterization of the Bulk Recombination in Hydrogenated Amorphous Silicon Solar Cells

Published online by Cambridge University Press:  21 March 2011

J. Deng
Affiliation:
Center for Thin Film Devices, the Pennsylvania State University, University Park, PA 16802
J.M. Pearce
Affiliation:
Center for Thin Film Devices, the Pennsylvania State University, University Park, PA 16802
V. Vlahos
Affiliation:
Center for Thin Film Devices, the Pennsylvania State University, University Park, PA 16802
R.W. Collins
Affiliation:
Center for Thin Film Devices, the Pennsylvania State University, University Park, PA 16802
C.R. Wronski
Affiliation:
Center for Thin Film Devices, the Pennsylvania State University, University Park, PA 16802
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Abstract

Dark forward bias current, JD-V, characteristics offer a probe for characterizing carrier recombination and the defect states in the intrinsic layers of hydrogenated amorphous silicon (a-Si:H) solar cells. Detailed studies were carried out on such characteristics for the cells with optimized p/i interfaces and high quality i-layers in which the current transport is bulk recombination dominated. It was found that the diode quality factor n is not a constant with bias voltages as has been generally considered. Instead, it can be best described through the bias dependent differential diode quality factors, n(V) = [kT/q]−1[d(lnJD)/dV]−1, whose magnitude and shape reflect the gap state distribution in the corresponding bulk i-layers. The n(V) characteristics obtained on cell structures with both hydrogen diluted and undiluted i-layers have been utilized in characterizing the differences in the distribution of defect states in the two i-layers both in annealed state as well as after creating light induced defects. In the characterization of the Staebler-Wronski Effect (SWE) using JD-V characteristics, a newphenomenon is observed – relaxation of light induced defect states created by 1 sun illumination at 25°C, which is also found in the follow-on studies on the photo-conductivities of corresponding thin films.

Type
Research Article
Copyright
Copyright © Materials Research Society 2004

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References

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