Disclosed is a method for preparing polycrystalline silicon ingot. The preparation method comprises: coating inner wall of the crucible with a layer of silicon nitride, followed by laying a layer of crushed silicon and feeding silicon in the crucible; the crushed silicon is laid in random order, and the layer of crushed silicon forms a supporting structure having numerous holes; melting the silicon to form molten silicon by heating, when solid-liquid interface reach the surface of the layer of crushed silicon or when the layer of crushed silicon melt partially, regulating thermal field to achieve supercooled state to grow crystals;after the crystallization of molten silicon is completely finished, performing annealing and cooling to obtain polycrystalline silicon ingot. By adopting the preparation method, a desirable initial nucleus can be obtained for a polycrystalline silicon ingot, so as to reduce dislocation multiplication during the growth of the polycrystalline silicon ingot.

Disclosed is a method for preparing polycrystalline silicon ingot. The preparation method comprises: randomly laying seed crystals with unlimited crystal orientation at the bottom of crucible to form a layer of seed crystals and obtaining disordered crystalline orientations; providing molten silicon above the layer of seed crystals, controlling the temperature at the bottom of the crucible, making the layer of seed crystals not completely melted; controlling the temperature inside the crucible, making the molten silicon growing above the seed crystals, the molten silicon inheriting the structure of the seed crystals, then obtaining polycrystalline silicon ingot. By adopting the preparation method, a desirable initial nucleus can be obtained for a polycrystalline silicon ingot, so as to reduce dislocation multiplication during the growth of the polycrystalline silicon ingot.

Disclosed is a method for preparing polycrystalline silicon ingot. The preparation method comprises: randomly laying seed crystals with unlimited crystal orientation at the bottom of crucible to form a layer of seed crystals and obtaining disordered crystalline orientations; providing molten silicon above the layer of seed crystals, controlling the temperature at the bottom of the crucible, making the layer of seed crystals not completely melted; controlling the temperature inside the crucible, making the molten silicon growing above the seed crystals, the molten silicon inheriting the structure of the seed crystals, then obtaining polycrystalline silicon ingot. By adopting the preparation method, a desirable initial nucleus can be obtained for a polycrystalline silicon ingot, so as to reduce dislocation multiplication during the growth of the polycrystalline silicon ingot.

A polycrystalline silicon column is provided. The polycrystalline silicon column includes a plurality of silicon grains grown along a crystal-growing direction. In the crystal-growing direction, the average grain size of the silicon grains and the resistivity of the polycrystalline silicon column have opposite variation in their trends, the average grain size of the silicon grains and the oxygen content of the polycrystalline silicon column have opposite variation in their trends, and the average grain size of the silicon grains and the defect area ratio of the polycrystalline silicon column have the same variation in their trends. The overall average defect area ratio of the polycrystalline silicon column is less than or equal to 2.5%.

A polycrystalline silicon column is provided. The polycrystalline silicon column includes a plurality of silicon grains grown along a crystal-growing direction. In the crystal-growing direction, the average grain size of the silicon grains and the resistivity of the polycrystalline silicon column have opposite variation in their trends, the average grain size of the silicon grains and the oxygen content of the polycrystalline silicon column have opposite variation in their trends, and the average grain size of the silicon grains and the defect area ratio of the polycrystalline silicon column have the same variation in their trends. The overall average defect area ratio of the polycrystalline silicon column is less than or equal to 2.5%.

A polycrystalline silicon wafer is provided. The polycrystalline silicon wafer, includes a plurality of silicon grains, wherein the carbon content of the polycrystalline silicon wafer is greater than 4 ppma, and the resistivity of the polycrystalline silicon wafer is greater than or equal to 1.55 -cm.

A method of fabricating a poly-crystalline silicon ingot includes: (a) loading a nucleation promotion layer onto a bottom of a mold; (b) providing a silicon source on the nucleation promotion layer in the mold; (c) heating the mold until the silicon source is melted into a silicon melt completely; (d) controlling at least one thermal control parameter regarding the silicon melt continually to enable the silicon melt to nucleate on the nucleation promotion layer such that a plurality of silicon grains grow in the vertical direction; (e) controlling the at least one thermal control parameter to enable the plurality of the silicon grains to continuously grow with an average grain size increasing progressively in the vertical direction until entirety of the silicon melt is solidified to obtain the poly-crystalline silicon ingot, wherein the nucleation promotion layer is loaded by spreading a plurality of mono-Si particles over the bottom of the mold.

A directional solidification furnace includes one or more movable cooling plates disposed beneath a crucible. In a first position, the cooling plates are free from contact with a crucible support positioned adjacent the crucible. In a second position, the cooling plates are in contact with the crucible support. A control system is used to control the amount of force exerted by the cooling plates against the crucible.

A directional solidification furnace includes one or more movable cooling plates disposed beneath a crucible. In a first position, the cooling plates are free from contact with a crucible support positioned adjacent the crucible. In a second position, the cooling plates are in contact with the crucible support. A control system is used to control the amount of force exerted by the cooling plates against the crucible.

An apparatus to purify a melt is disclosed. A first portion of a melt in a chamber is frozen in a first direction. A fraction of the first portion is melted in the first direction. A second portion of the melt remains frozen. The melt flows from the chamber and the second portion is removed from the chamber. The freezing concentrates solutes in the melt and second portion. The second portion may be a slug with a high solute concentration. This system may be incorporated into a sheet forming apparatus with other components such as, for example, pumps, filters, or particle traps.