Methods and apparatus for manufacturing monocrystalline cast silicon and monocrystalline cast silicon bodies for photovoltaics

A method of manufacturing cast silicon, comprising:

• placing a geometric arrangement of a plurality of silicon seed crystals comprising monocrystalline silicon on at least one surface in a crucible having one or more side walls heated to at least the melting temperature of silicon and at least one wall for cooling, wherein the geometric arrangement includes close-packed polygons;
• placing molten silicon in contact with the geometric arrangement of the silicon seed crystals;
• melting a desired portion of the at least one seed crystal by measuring the extent of melting;
• and
• forming a solid body comprising near-monocrystalline silicon, having at least two dimensions each being at least about 10 cm, by cooling the molten silicon to control crystallization, wherein the forming includes forming a solid-liquid interface at an edge of the molten silicon that parallels the at least one wall for cooling, the interface being controlled during the cooling so as to move in a direction that increases a distance between the molten silicon and the at least one wall for cooling.

A method of manufacturing cast silicon, comprising:

• arranging a plurality of silicon seed crystals comprising monocrystalline silicon in a predetermined pattern on at least two surfaces of a crucible;
• placing molten silicon in contact with the monocrystalline silicon seed crystals;
• and
• forming a solid body comprising near-monocrystalline silicon, having at least two dimensions each being at least about 10 cm, by cooling the molten silicon from the at least two surfaces of the crucible to control crystallization, wherein the forming includes controlling a solid-liquid interface at an edge of the molten silicon during the cooling so as to move in a direction that increases a distance between the molten silicon and the at least two surfaces of the crucible.

A method of manufacturing cast silicon, comprising:

• placing silicon feedstock in contact with at least one silicon seed crystal comprising monocrystalline silicon on at least one surface;
• heating the silicon feedstock and the at least one silicon seed crystal to the melting temperature of silicon;
• controlling the heating so that the at least one silicon seed crystal does not melt completely, the controlling comprising maintaining a .DELTA.T of about 0.1. degree. C./min or less, as measured on an outside surface of the crucible, after reaching the melting temperature of silicon elsewhere in the crucible;
• and,
• once the at least one silicon seed crystal is partially melted, forming a solid body comprising near-monocrystalline silicon by cooling the silicon.

A method of manufacturing cast silicon, comprising:

• placing a geometric arrangement of a plurality of silicon seed crystals comprising monocrystalline silicon on at least one surface in a crucible, wherein the geometric arrangement includes close-packed polygons;
• placing silicon feedstock in contact with the plurality of silicon seed crystals on the at least one surface;
• heating the silicon feedstock and the plurality of silicon seed crystals to the melting temperature of silicon;
• controlling the heating so that the plurality of seed crystals does not melt completely, the controlling comprising maintaining a .DELTA.T of about 0.1. degree. C./min or less, as measured on an outside surface of the crucible, after reaching the melting temperature of silicon elsewhere in the crucible;
• and,
• once the at least one silicon seed crystal is partially melted, forming a solid body comprising near-monocrystalline silicon by cooling the silicon.

A method of manufacturing cast silicon, comprising:

• arranging a plurality of silicon seed crystals comprising near-monocrystalline silicon in a predetermined pattern on at least two surfaces of a crucible placing silicon feedstock in contact with the plurality of silicon seed crystals on the at least two surfaces;
• heating the silicon feedstock and the plurality of silicon seed crystals to the melting temperature of silicon;
• controlling the heating so that the plurality of silicon seed crystals does not melt completely, the controlling comprising maintaining a .DELTA.T of about 0.1. degree. C./min or less, as measured on an outside surface of the crucible, after reaching the melting temperature of silicon elsewhere in the crucible;
• and,
• once at least one monocrystalline silicon seed crystal is partially melted, forming a solid body comprising near-monocrystalline silicon by cooling the silicon.

A method of manufacturing cast silicon, comprising:

• placing molten silicon in contact with at least one silicon seed crystal in a vessel having one or more side walls heated to at least the melting temperature of silicon, the at least one silicon seed crystal arranged to cover an entire or substantially an entire area of a surface of the vessel;
• melting a desired portion of the at least one seed crystal by measuring the extent of melting;
• and
• forming a solid body comprising near-monocrystalline silicon, having at least two dimensions each being at least about 10 cm, by cooling the molten silicon to control crystallization.