Molded articles and methods for forming molded articles are provided. For example, a molded article comprises a first region formed by a first casting material and a second region formed by mixing a molten or liquid portion of the first casting material and a second casting material. The first casting material is a molten, liquid, or fluid metal alloy, and the second casting material is a molten or fluid metal alloy. The first casting material has a different chemical composition than the second casting material. The first region and the second region are cast as one integral casting using directional solidification, and the first region and the second region have different microstructure patterns. The molded article has a lower concentration of impurities than were present in the first and second casting materials, and an interface between the first region and the second region is devoid of an oxidation layer.

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: 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.

A crystalline silicon ingot and a method of fabricating the same are disclosed. The crystalline silicon ingot of the invention includes multiple silicon crystal grains growing in a vertical direction of the crystalline silicon ingot. The crystalline silicon ingot has a bottom with a silicon crystal grain having a first average crystal grain size of less than about 12 mm. The crystalline silicon ingot has an upper portion, which is about 250 mm away from said bottom, with a silicon crystal grain having a second average crystal grain size of greater than about 14 mm.

A crystalline silicon ingot and a method of fabricating the same are disclosed. The crystalline silicon ingot of the invention includes multiple silicon crystal grains growing in a vertical direction of the crystalline silicon ingot. The crystalline silicon ingot has a bottom with a silicon crystal grain having a first average crystal grain size of less than about 12 mm. The crystalline silicon ingot has an upper portion, which is about 250 mm away from said bottom, with a silicon crystal grain having a second average crystal grain size of greater than about 14 mm.

A gettered polycrystalline group III metal nitride is formed by heating a group III metal with an added getter in a nitrogen-containing gas. Most of the residual oxygen in the gettered polycrystalline nitride is chemically bound by the getter. The gettered polycrystalline group III metal nitride is useful as a raw material for ammonothermal growth of bulk group III nitride crystals.

A gettered polycrystalline group III metal nitride is formed by heating a group III metal with an added getter in a nitrogen-containing gas. Most of the residual oxygen in the gettered polycrystalline nitride is chemically bound by the getter. The gettered polycrystalline group III metal nitride is useful as a raw material for ammonothermal growth of bulk group III nitride crystals.

The present disclosure provides a polycrystalline silicon ingot. The polycrystalline silicon ingot has a vertical direction and includes a nucleation promotion layer located at a bottom of the polycrystalline silicon ingot, and silicon grains grown along the vertical direction, wherein the silicon grains include at least three crystal directions. The coefficient of variation of grain area in a section above the nucleation promotion layer of the polycrystalline silicon ingot increases along the vertical direction.

The present disclosure provides a polycrystalline silicon ingot. The polycrystalline silicon ingot has a vertical direction and includes a nucleation promotion layer located at a bottom of the polycrystalline silicon ingot, and silicon grains grown along the vertical direction, wherein the silicon grains include at least three crystal directions. The coefficient of variation of grain area in a section above the nucleation promotion layer of the polycrystalline silicon ingot increases along the vertical direction.

Present disclosure provides a multicrystalline silicon (mc-Si) brick, including a bottom portion starting from a bottom to a height of 100 mm, a middle portion starting from the height of 100 mm to a height of 200 mm; and a top portion starting from the height of 200 mm to a top. A percentage of incoherent grain boundary in the bottom portion is greater than a percentage of incoherent grain boundary in the top portion. Present disclosure also provides a multicrystalline silicon (mc-Si) wafer. The mc-Si wafer includes a percentage of non- grain boundary from about 60 to about 75 and a percentage of 3 grain boundary from about 12 to about 25.