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Microcrystalline Silicon Germanium: An Attractive Bottom-Cell Material for Thin-Film Silicon-Based Tandem-Solar-Cells

Published online by Cambridge University Press:  15 February 2011

Gautam Ganguly
Affiliation:
Thin Film Silicon Solar Cells Superlab, Electrotechnical Laboratory, Tsukuba City, 305, Japan
Tom Ikeda
Affiliation:
Thin Film Silicon Solar Cells Superlab, Electrotechnical Laboratory, Tsukuba City, 305, Japan
Kei Kajiwara
Affiliation:
Thin Film Silicon Solar Cells Superlab, Electrotechnical Laboratory, Tsukuba City, 305, Japan
Akihisa Matsuda
Affiliation:
Thin Film Silicon Solar Cells Superlab, Electrotechnical Laboratory, Tsukuba City, 305, Japan
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Abstract

We have prepared hydrogenated macrocrystalline silicon germanium by plasma enhanced CVD of a mixture of silane and germane gas diluted with hydrogen. The growth conditions have been systematically controlled to obtain large (∼400Å) crystallites of silicon-germanium as observed using Raman scattering and x-ray diffraction. The dangling bond (germanium) density has been reduced to <5×1016 cm−3 at low substrate temperatures (∼150°C). The optical absorption spectra of the 50% Ge containing material is red-shifted compared to microcrystalline silicon, consistent with a reduction of the indirect optical gap to 0.9eV. Schottky type cells fabricated using Au on an n+ crystalline silicon substrate confirm that the long wavelength response is remarkably enhanced in this material.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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