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impurity effects in silicon for high efficiency solar cellsModel analyses indicate that sophisticated solar cell designs including, e.g., back surface fields, optical reflectors, surface passivation, and double layer antireflective coatings can produce devices with conversion efficiencies above 20 percent (AM1). To realize this potential, the quality of the silicon from which the cells are made must be improved; and these excellent electrical properties must be maintained during device processing. As the cell efficiency rises, the sensitivity to trace contaminants also increases. For example, the threshold Ti impurity concentration at which cell performance degrades is more than an order of magnitude lower for an 18-percent cell. Similar behavior occurs for numerous other metal species which introduce deep level traps that stimulate the recombination of photogenerated carriers in silicon. Purification via crystal growth in conjunction with gettering steps to preserve the large diffusion length of the as-grown material can lead to the production of devices with efficiencies aboved 18 percent, as has been verified experimentally.
Document ID
Document Type
Reprint (Version printed in journal)
Hopkins, R. H.
(Westinghouse Research and Development Center Pittsburgh, PA, United States)
Rohatgi, A.
(Westinghouse Research and Development Center Pittsburgh, PA, United States)
Date Acquired
August 12, 2013
Publication Date
May 1, 1986
Publication Information
Publication: Journal of Crystal Growth
Volume: 75
ISSN: 0022-0248
Subject Category
Distribution Limits