DR. PESHOTAN SOHRAB KOTVAL, M.D., PH.D.
Radiology at Verne Pl, Hartsdale, NY

4193975, Mar 18, 1980

Nov 21, 1977

5/853759

Peshotan S. Kotval - Hartsdale NY
Harold B. Strock - North Tarrytown NY

Union Carbide Corporation - New York NY

B01J 1720, C01B 3302

423348

Silicon platelets essentially free of iron are precipitated from a solution of metallurgical grade silicon in molten aluminum and are melted in contact with silica slag to produce a refined metallurgical silicon (RMS). Multigrained boules of said RMS are pulled by the Czochralski method on a rotating silicon seed rod from a melt of said RMS. Alternatively, the silicon-slag melt can be directionally solidified to produce a directionally solidified refined metallurgical silicon (DS/RMS) separated from a region of solidified melt having a high concentration of impurities rejected by the silicon as it solidifies. Multigrained DS/RMS boules are pulled from a melt of said DS/RMS. Alternatively, the DS/RMS is remelted and directionally solidified a second time with single crystal DS/RMS boules being pulled from a melt of the twice directionally solidified material. The thus-pulled, multigrained RMS and DS/RMS and single crystal DS/RMS materials are low-cost products having a substantially higher impurity content than in conventional high purity semiconductor grade silicon while, at the same time, having desirable solar cell properties.

4124410, Nov 7, 1978

Nov 21, 1977

5/853770

Peshotan S. Kotval - Hartsdale NY
Harold B. Strock - North Tarrytown NY

Union Carbide Corporation - New York NY

H01L 3106

136 89TF

Epitaxial and diffusion-type planar diodes and solar cells utilize low-cost refined metallurgical silicon substrates having a substantially higher impurity content than conventional high-cost, high purity semiconductor grade silicon. The epitaxial type products have an n-on-p-on-p substrate configuration, while the diffusion-type products have pentavalent impurities diffused therein to form a p-n junction in the low cost silicon substrate. One embodiment employs a multigrained refined metallurgical silicon (RMS) prepared by precipitating essentially iron-free silicon platelets from a solution of metallurgical grade silicon in molten aluminum, melting said refined platelets, in contact with a silica slag and pulling silicon boules from a melt of said refined metallurgical silicon (RMS). By directionally solidifying the refined silicon-slag melt, a multigrained, directionally solidified refined metallurgical silicon (DS/RMS) is obtained, with boules being pulled from a melt thereof for use as said low-cost substrate. The DS/RMS may also be re-melted and directionally solidified a second time with the boules being pulled from said twice directionally-solidified material being a desirable, low-cost, single crystal material suitable for use as said substrate for planar diode and solar cell applications.

4193974, Mar 18, 1980

Nov 21, 1977

5/853763

Peshotan S. Kotval - Hartsdale NY
Harold B. Strock - North Tarrytown NY

Union Carbide Corporation - New York NY

C01B 3302

423348

Silicon platelets essentially free of iron are precipitated from a solution of metallurgical grade silicon in molten aluminum and are melted in contact with silica slag to produce a refined metallurgical silicon. The silicon-slag melt solidified in a unidirectional manner so as to directionally solidify said silicon. A directionally solidified refined metallurgical silicon (DS/RMS) ribbon is pulled from a melt of the thus-refined silicon. This DS/RMS ribbon is a low-cost product having a substantially higher impurity content level than in conventional high purity semiconductor grade silicon while, at the same time, being useful for solar cell applications.

4195067, Mar 25, 1980

Nov 21, 1977

5/853758

Peshotan S. Kotval - Hartsdale NY
Harold B. Strock - North Tarrytown NY

Union Carbide Corporation - New York NY

C01B 3302

423348

Silicon platelets essentially free of iron are precipitated from a solution of metallurgical grade silicon in molten aluminum and are melted in contact with silica slag to produce a refined metallurgical silicon (RMS). By directionally solidifying the refined silicon-slag melt, a directionally solidified refined metallurgical silicon (DS/RMS) is separated from a region of solidified melt having a high concentration of impurities rejected by the silicon as it solidifies. The resulting RMS and DS/RMS materials are low-cost, multigrained products having a substantially higher impurity content than in conventional high purity semiconductor grade silicon while, at the same time, have suitable properties for desirable solar cell and other silicon applications.