Hostname: page-component-848d4c4894-4rdrl Total loading time: 0 Render date: 2024-06-21T02:37:12.692Z Has data issue: false hasContentIssue false
  • English
  • Français

An Assessment of a-SiGe:H Alloys with a Band GaP of 1.5Ev as to their Suitability for Solar Cell Applications

Published online by Cambridge University Press:  28 February 2011

B. Von Roedern ,
A.H. Mahan ,
T.J. McMahon  and
A. Madan
B. Von Roedern
Affiliation:
Glasstech Solar, Inc., 12441 W. 49th Ave., Wheatridge, CO 80033
A.H. Mahan
Affiliation:
Solar Energy Research Institute, Golden, CO 80401
T.J. McMahon
Affiliation:
Solar Energy Research Institute, Golden, CO 80401
A. Madan
Affiliation:
Glasstech Solar, Inc., 12441 W. 49th Ave., Wheatridge, CO 80033
Get access

Abstract

Hydrogenated amorphous silicon germanium alloys a-Si1-xGex:H are being actively investigated for their application as a low band gap material in cascade solar cells [1,2]. To date, such alloys produce material of reasonable electronic quality only if the Ge-content is kept low (<40 at.%) such that the band gap is not decreased much below 1.5 eV. Conversion efficiencies of -5% have been obtainedwith alloys having such a band gap, and tandem cells have shown conversion efficiencieswhich are lower than those of good quality single layer a-Si:H devices. Thus, the performance of alloys is well below that necessary to achieve conversion efficiencies of >16%, which are ultimately hoped to be obtained using the cascade approach [2]. Other low band gap alloys such as a-Si1-xSnx:H have been shown to be even less suitable with regard to their electronic properties [3]. The cause of the degradation in electronic properties with increased alloying is not yet understood. Factors such as preferential attachment of H to Si rather than Ge [4] or microstructure observed in alloys have been suggested as a cause for the electronic degradation, [5,6] but no unique correlations have been established between such findings and the electronic properties.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 49: Symposium F – Materials Issues in Applications of Amorphous Silicon Technology , 1985 , 167
Copyright
Copyright © Materials Research Society 1985

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Higaki, Y., Aiga, M., Terazono, S., and Yukimoto, Y., Technical Digest of the Int. PVSEC-1, Kobe, (1984), p.209.Google Scholar
2. Madan, A., presented at ASES conference Minneapolis, 1983. Also in Madan, A. “Silicon Processing for Photovoltaics”, Ed. Khattak, C.P. and Ravi, K.V.; to be published by North Holland Publishing.Google Scholar
3. Mahan, A.H., Roedern, B. von, Williamson, D.L. and Madan, A., p.92.Google Scholar
4. Paul, W., Paul, D.K., B. von Roedern, Blake, J. and Oguz, S., Phys. Rev. Lett. 46, (1981), 1016.CrossRefGoogle Scholar
5. Mackenzie, K.D., Eggert, J.R., Leopold, D.J., Li, Y.M., Lin, S. and Paul, W., Phys. Rev. B31, (1985), 2198.CrossRefGoogle Scholar
6. Yacobi, B.G., B. von Roedern, Mahan, A.H., and Jones, K.M., Phys. Rev. B., accepted for publication.Google Scholar
7. Roedern, B. von, Mahan, A.H., Williamson, D.L. and Madan, A., J. Non-Cryst. Solids 66, (1984) 13.Google Scholar
8. Jackson, W.B. and Amer, N.M.., Phys. Rev. B 25, (1982) 5559.Google Scholar
9. McMahon, T.J., Yacobi, B.G., Sadlon, K., Dick, J. and Madan, A.., J. Non-Cryst. Solids 66, (1984) 375.Google Scholar
10. McMahon, T.J. and Madan, A., to be published.Google Scholar
11. Weisfield, R.L. (Thesis, Harvard U. 1983) reported for example that the photoluminescence intensity (which is limited by the competing non-radiative recombination process) of sputtered a-SiGe:H with g(EF)=1017 cm- 3 eV- 1 is a factor of -7 less than that of a-Si:H with the same g(EF).Google Scholar
12.If we assume that charged dangling bond states in addition to their neutral counterparts provide recombination centers (represented by an average capture rate in our recombination model), a decrease in the correlation energy upon alloying would increase the ratio of charged to neutral states, which could possibly account for the increased average capture rates observed in the alloys.Google Scholar