Abstract: The present invention relates to multicrystalline p-type silicon wafers with high lifetime. The silicon wafers contain 0.2-2.8 ppma boron and 0.06-2.8 ppma phosphorous and/or arsenic and have been subjected to phosphorous diffusion and phosphorous gettering at a temperature of above 925° C. The invention further relates to a method for production of such multicrystalline silicon wafers and to solar cells comprising such silicon wafers.

Abstract: A coating system for a mould for the directional solidification of silicon. The coating is applied as an aqueous slurry of silicon nitride particle, carbon black and microsilica.

Abstract: 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.

Abstract: The present invention relates to a calcium-silicate based slag having a phosphorus content of less than 3 ppmw. The invention further relates to a method for producing low phosphorus calcium-silicate based slag, where molten calcium-silicate based slag is treated with a molten ferrosilicon alloy in a vessel, whereby phosphorus in the calcium-silicate based slag is transferred to the ferrosilicon alloy, and a low phosphorus calcium-silicate based slag is removed from the vessel.

Abstract: A method for making solar grade silicon from metallurgical grade silicon is accomplished by treating a calcium silicate based slag with ferrosilicon in the first vessel so as to obtain a purification of the calcium silicate based slag. In a second vessel, the purified calcium based silicate slag is used to treat metallurgical grade silicon in order to obtain a solar grade silicon. The purification of calcium silicate based slag in the first vessel is accomplished to reduce phosphorous to a level of less than 3 ppmw.

Abstract: The present invention relates to multicrystalline p-type silicon wafers with high lifetime. The silicon wafers contain 0.2-2.8 ppma boron and 0.06-2.8 ppma phosphorous and/or arsenic and have been subjected to phosphorous diffusion and phosphorous gettering at a temperature of above 925° C. The invention further relates to a method for production of such multicrystalline silicon wafers and to solar cells comprising such silicon wafers.

Abstract: A coating system for a mould for the directional solidification of silicon. The coating is applied as an aqueous slurry of silicon nitride particle, carbon black and microsilica.

Abstract: A method for making solar grade silicon from metallurgical grade silicon is disclosed, which including, treating a calcium-silicate based slag by molten calcium-silicate based slag in a first vessel, whereby phosphorous in the calcium-silicate based slag is transferred to the ferrosilicon alloy producing a calcium-silicate based containing less than 3 ppmw phosphorous; obtaining the calcium-silicate based slag containing less than 3 ppmw phosphorous from the first vessel; treating a molten metallurgical grade silicon in a second vessel with the calcium-silicate based slag containing less than 3 ppmw phosphorous to reduce the content of phosphorous, boron and iron in the metallurgical grade silicon; and removing solar grade silicon with low content of phosphorous, boron and iron from the second vessel.

Abstract: 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.

Abstract: The present invention relates to a calcium-silicate based slag having a phosphorous content of less than 3 ppmw. The invention further relates to a method for producing a low phosphorous calcium-silicate based slag, where molten calcium-silicate based slag is treated with a molten ferrosilicon alloy in a vessel, whereby phosphorous in the calcium-silicate based slag is transferred to the ferrosilicon alloy, and a low phosphorous calcium-silicate to based slag is removed from the vessel.

Abstract: 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.

Abstract: 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.

Abstract: The present invention relates to a calcium-silicate based slag having a phosphorous content of less than 3 ppmw. The invention further relates to a method for producing a low phosphorous calcium-silicate based slag, where molten calcium-silicate based slag is treated with a molten ferrosilicon alloy in a vessel, whereby phosphorous in the calcium-silicate based slag is transferred to the ferrosilicon alloy, and a low phosphorous calcium-silicate to based slag is removed from the vessel.

Abstract: The present invention relates to a method for determination of the electrode tip position for consumable electrodes in electric smelting furnaces, which electrodes being submerged in the furnace charge. The voltage between two geometrically displaced points on the outside of the steel wall of the furnace pot is measured during operation of the furnace, points being situated as close as possible to the electrode for which the electrode tip position is to be determined, and as far away as possible from the other electrodes in the furnace. The electrode current for the electrode for which the electrode tip position is to be determined, is recorded at the same time as the voltage between the two points are measured, whereafter the difference between measured voltage between the two points and measured electrode current is calculated, and where the absolute value of difference increases when the electrode tip position increases and decreases when the absolute value of difference decreases.