Patents by Inventor Kenneth Friestad
Kenneth Friestad has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 8580036Abstract: The method and apparatus includes a vessel having a bottom and sidewalls arranged to house the material in a molten state. A temperature controlled horizontally oriented, cooling plate is movable into and out of the top of the molten material. When the cooling plate is lowered into the top of the melt, an ingot of solid silicon is solidified downwards.Type: GrantFiled: May 10, 2006Date of Patent: November 12, 2013Assignee: Elkem Solar ASInventor: Kenneth Friestad
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Patent number: 7931883Abstract: The silicon feedstock for solar cells is made from metallurgical grade silicon by the successive steps of treating the silicon with a calcium-silicate slag, solidifying the treated silicon, leaching the solid silicon with acid, remelting the leached silicon, resolidifying the remelted silicon into an ingot, removing the upper part of the ingot and then crushing and sizing.Type: GrantFiled: April 23, 2008Date of Patent: April 26, 2011Assignee: Elkem ASInventors: Erik Enebakk, Kenneth Friestad, Ragnar Tronstad, Cyrus Zahedi, Christian Dethloff
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Publication number: 20100034723Abstract: A method for the directional solidification of silicon or other materials. A cooled plate is lowered into a silicon melt and an ingot of solid silicon is solidified downwards.Type: ApplicationFiled: August 12, 2009Publication date: February 11, 2010Applicant: ELKEM SOLAR ASInventor: Kenneth FRIESTAD
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Publication number: 20080206123Abstract: The present invention relates to silicon feedstock for producing directionally solidified silicon ingots, thin sheets and ribbons for the production of silicon wafers for PV solar cells where the silicon feedstock contains between 0.2 and 10 ppma boron and between 0.1 and 10 ppma phosphorus distributed in the material. The invention further relates to directionally solidified silicon ingot or thin silicon sheet or ribbon for making wafers for solar cells containing between 0.2 ppma and 10 ppma boron and between 0.1 ppma and 10 ppma phosphorus distributed in the ingot, said silicon ingot having a type change from p-type to n-type or from n-type to p-type at a position between 40 and 99% of the ingot height or sheet of ribbon thickness and having a resistivity profile described by an exponential curve having a starting value between 0.4 and 10 ohm cm and where the resistivity value increases towards the type change point.Type: ApplicationFiled: April 23, 2008Publication date: August 28, 2008Applicant: ELKEM ASAInventors: Erik Enebakk, Kenneth Friestad, Ragnar Tronstad, Cyrus Zahedi, Christian Dethloff
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Publication number: 20080196209Abstract: A method for the directional solidification of silicon or other materials.Type: ApplicationFiled: May 10, 2006Publication date: August 21, 2008Applicant: ELKEM SOLAR ASInventor: Kenneth Friestad
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Patent number: 7381392Abstract: The present invention relates to silicon feedstock for producing directionally solidified silicon ingots, thin sheets and ribbons for the production of silicon wafers for PV solar cells where the silicon feedstock contains between 0.2 and 10 ppma boron and between 0.1 and 10 ppma phosphorus distributed in the material. The invention further relates to directionally solidified silicon ingot or thin silicon sheet or ribbon for making wafers for solar cells containing between 0.2 ppma and 10 ppma boron and between 0.1 ppma and 10 ppma phosphorus distributed in the ingot, said silicon ingot having a type change from p-type to n-type or from n-type to p-type at a position between 40 and 99% of the ingot height or sheet or ribbon thickness and having a resistivity profile described by an exponential curve having a starting value between 0.4 and 10 ohm cm and where the resistivity value increases towards the type change point.Type: GrantFiled: January 12, 2004Date of Patent: June 3, 2008Assignee: Elkem ASInventors: Erik Enebakk, Kenneth Friestad, Ragnar Tronstad, Cyrus Zahedi, Christian Dethloff
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Publication number: 20080029019Abstract: The present invention relates to a method for the production of directionally solidified Czochralski, float zone or multicrystalline silicon ingots or thin sheets or ribbon for making wafers for solar cells from silicon feedstock initially containing between 0.2 ppma and 10 ppma boron and between 0.1 ppma and 10 ppma phosphorous. If the boron content in the silicon feedstock is higher than the phosphorous content, the boron content in the molten silicon is kept higher than the phosphorous content during the directional solidification process by adding boron to the molten silicon in order to extend the part of the directionally solidified ingot or the thin sheet or ribbon solidifying as p-type material.Type: ApplicationFiled: November 17, 2005Publication date: February 7, 2008Applicant: ELKEM SOLAR ASInventors: Christian Dethloff, Kenneth Friestad
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Patent number: 7232544Abstract: The invention relates to an apparatus for continuous slag treatment of molten silicon for removal of one a more impurity elements from the silicon, the apparatus comprising a vessel (1) intended to contain molten silicon and liquid slag.Type: GrantFiled: October 7, 2002Date of Patent: June 19, 2007Assignee: Elkem ASInventors: Torfinn Buseth, Kenneth Friestad, Pal Runde
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Publication number: 20070128099Abstract: The present invention relates to silicon feedstock for producing directionally solidified silicon ingots, thin sheets and ribbons for the production of silicon wafers for PV solar cells where the silicon feedstock contains between 0.2 and 10 ppma boron and between 0.1 and 10 ppma phosphorus distributed in the material. The invention further relates to directionally solidified silicon ingot or thin silicon sheet or ribbon for making wafers for solar cells containing between 0.2 ppma and 10 ppma boron and between 0.1 ppma and 10 ppma phosphorus distributed in the ingot, said silicon ingot having a type change from p-type to n-type or from n-type to p-type at a position between 40 and 99% of the ingot height or sheet or ribbon thickness and having a resistivity profile described by an exponential curve having a starting value between 0.4 and 10 ohm cm and where the resistivity value increases towards the type change point.Type: ApplicationFiled: January 12, 2004Publication date: June 7, 2007Applicant: ELKEM ASAInventors: Erik Enebakk, Kenneth Friestad, Ragnar Tronstad, Cyrus Zahedi, Christian Dethloff
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Patent number: 6861040Abstract: The invention relates to a method for purification of metallurgical grade silicon where a calcium containing compound is added to molten silicon prior to or after the silicon is tapped from the furnace. The silicon is cast and solidified at a relatively high cooling rate and the solidified silicon is crushed and subjected to a purification process consisting of two leaching steps. In the first leaching step the silicon is treated with an aqueous solution of FeCl3 or FeCl3 and HCl which causes disintegration of the silicon, and in the second leaching step the silicon is treated with an aqueous solution of HF or HF/HNO3. Calcium-containing compound is added to the molten silicon in an amount necessary to provide between 0.3 and 0.95% by weight of calcium in the molten silicon and the weight ratio between Al and Fe in the molten silicon is regulated to between 0.5 and 2.0 by addition of aluminum to the molten silicon.Type: GrantFiled: August 11, 2000Date of Patent: March 1, 2005Assignee: Elkem ASAInventors: Bruno Ceccaroli, Kenneth Friestad
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Publication number: 20040258588Abstract: The invention relates to an apparatus for continuous slag treatment of molten silicon for removal of one a more impurity elements from the silicon, the apparatus comprising a vessel (1) intended to contain molten silicon and liquid slag.Type: ApplicationFiled: April 8, 2004Publication date: December 23, 2004Inventors: Torfinn Buseth, Kenneth Friestad, Pal Runde