Abstract: A material handling system for moving material from a storage device to a receiver comprises a counter rotating double screw feeder extending from the storage device to the receiver. The counter rotating double screw feeder comprises an outer screw feed member; an inner screw feed member; where the outer screw feed member being positioned in an outer screw feed member tube; and the inner screw feed member being positioned in an inner screw feed member tube. The material is feed from the storage device to the process tube via the outer screw feed member; the inner screw feed member removes gas and byproducts from the receiver.

Abstract: The invention relates to a silicon sheet having columnar grains extending axially through the sheet from one free surface of the sheet to the other free surface. The sheet has an electrical resistivity in the range of 0.1 to 10 ohm-cm.

Abstract: The invention relates to improved techniques for manufacturing columnar-grained polycrystalline sheets which have particular utility as substrates or wafers for solar cells. The sheet is made from silicon on a setter material which supports the silicon material. The setter material and silicon are subjected to a thermal profile all of which promote columnar growth. The thermal profile sequentially creates a melt region where a thin-film capping layer grows at the top of the silicon, a nucleation region where preferential nucleation occurs at the capping-layer/molten-silicon interface, 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.