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Title: Advanced Czochralski silicon-growth technology for photovoltaic modules

Technical Report ·
DOI:https://doi.org/10.2172/6742778· OSTI ID:6742778

Large-area silicon sheet growth is one of the important elements of photovoltaic modules. In order to reduce the cost of these modules, a number of silicon sheet growth approaches encompassing both the ingot and the ribbon technology have been developed. Advancement of the Czochralski (Cz) growth method has been one of these approaches because of its existing broad technical base. Several economic analyses had indicated that large-diameter, multiple ingot growth using a single crucible with melt replenishment would be required for Cz growth to be economically viable. Based on the results of these analyses, two liquid and two solid feed melt replenishment approaches were initiated. The sequential solid feed melt replenishment approach, which demonstrated elements of technical feasibility, is described in detail in this paper. Growth results of multiple ingots (10-cm-diameter, totaling 100 kg; and 15-cm-diameter, totaling 150 kg weight per crucible) are presented. Solar cells were fabricated and analyzed to evaluate the effects of structure and chemical purities as a result of multiple growth. The results indicate that, with semiconductor-grade silicon, feedstock impurity build-up does not seem to degrade cell performance. For polycrystalline cells, the average efficiencies are 15 to 25% lower than those of single crystalline cells. Concerns regarding single crystal yields, crucible quality and growth speed are indicated, and present status and future research thrusts are also discussed.

Research Organization:
California Institute of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab. (JPL)
DOE Contract Number:
AI01-76ET20356
OSTI ID:
6742778
Report Number(s):
DOE/JPL-1012-70; ON: DE83002206
Country of Publication:
United States
Language:
English