Robert B. Hall - Newark DE Allen M. Barnett - Newark DE Jacob E. Brown - Newark DE Joseph C. Checchi - Newark DE David H. Ford - Wilmington DE Christopher L. Kendall - Wilmington DE William P. Mulligan - Hockessin DE James A. Rand - Oxford PA Todd R. Ruffins - Newark DE
Assignee:
AstroPower, Inc. - Newark DE
International Classification:
H01L 310392 H01L 310368 H01L 3118
US Classification:
136258
Abstract:
The invention relates to techniques for manufacturing columnar-grained polycrystalline sheets which have particular utility as substrates or wafers for solar cells. The sheet is made by applying granular silicon to a setter material which supports the granular material. The setter material and granular silicon are subjected to a thermal profile all of which promote columnar growth by melting the silicon from the top downwardly. The thermal profile sequentially creates a melt region at the top of the granular silicon and then a growth region where both liquid and a growing polycrystalline sheet layer coexist. An annealing region is created where the temperature of the grown polycrystalline silicon sheet layer is controllably reduced to effect stress relief.