Silicon materials task of the low cost solar array project (Part 2). Fourth quarterly report, July 1, 1976--September 30, 1976
During this quarter we have completed the growth of all contract-required Czochralski and silicon dendritic web crystals. The chemical analysis of all the Czochralski ingots is also finished. Preliminary mass spectroscopic evaluation of metal-doped web samples grown at 1.3 cm/min indicates that the effective distribution coefficients for Cu, Ni, and Cr all increase with growth rate as anticipated. For chromium the increase is almost 100 fold compared to the effective k for Czochralski ingots grown at 7.5 cm/hr. PCD lifetime measurements were completed on 46 ingots. The correlation between solar cell performance and PCD lifetime appears valid for all processed wafers except those containing Ti which give lower cell efficiency than would be predicted on the basis of lifetime alone. Solar cell measurements were completed in all but a few of the ingots grown during the contract. In particular, data has now been obtained on the second set of multiply-doped samples containing the impurity combinations Zr/Ti, Cr/Ni, and Cr/Cu/Ni. As in the case of ingots containing only Ti, the Zr/Ti sample shows severely degraded cell efficiency, only about 26% of the baseline. The Cr/Ni and Cr/Cu/Ni samples show efficiencies of 81 and 72% of baseline efficiency reflecting the small effects of Cu and Ni on cell performance and the stronger effect of Cr.
- Research Organization:
- Dow Corning Corp., Hemlock, MI (USA)
- DOE Contract Number:
- NAS-7-100-954331
- OSTI ID:
- 7228267
- Report Number(s):
- ERDA/JPL/954331-76/4
- Country of Publication:
- United States
- Language:
- English
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