Multicrystalline silicon brick and silicon wafer therefrom

Abstract

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-Σ grain boundary from about 60 to about 75 and a percentage of Σ3 grain boundary from about 12 to about 25.

What is claimed is: 
     
         1 . A multicrystalline silicon brick, comprising:
 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;   wherein a percentage of incoherent grain boundary in the bottom portion is greater than a percentage of incoherent grain boundary in the top portion.   
     
     
         2 . The multicrystalline silicon brick of  claim 1 , further comprising a preferred grain orientation of {112} in the bottom portion, the middle portion, and the top portion. 
     
     
         3 . The multicrystalline silicon brick of  claim 1 , wherein the incoherent grain boundary comprises non-Σ grain boundaries. 
     
     
         4 . The multicrystalline silicon brick of  claim 1 , a percentage of coherent grain boundary in the bottom portion is lower than a percentage of coherent grain boundary in the top portion. 
     
     
         5 . The multicrystalline silicon brick of  claim 4 , wherein the coherent grain boundary comprises Σ3 grain boundary. 
     
     
         6 . The multicrystalline silicon brick of  claim 5 , the percentage of Σ3 grain boundary being lower than the percentage of the non-Σ grain boundary and greater than other grain boundary being more incoherent than the Σ3 grain boundary. 
     
     
         7 . The multicrystalline silicon brick of  claim 3 , wherein the percentage of non-Σ grain boundaries is from about 65 to about 75 at the bottom portion. 
     
     
         8 . The multicrystalline silicon brick of  claim 6 , wherein the percentage of non-Σ grain boundary is greater than a summation of the percentage of Σ3 grain boundary and the percentage of other grain boundary being more incoherent than the Σ3 grain boundary. 
     
     
         9 . The multicrystalline silicon brick of  claim 5 , wherein the percentage of Σ3 grain boundaries is from about 12 to about 18 at the bottom portion. 
     
     
         10 . The multicrystalline silicon brick of  claim 1 , further comprising a nucleation promotion layer under the bottom portion, wherein the nucleation promotion layer comprises a plurality of beads. 
     
     
         11 . The multicrystalline silicon brick of  claim 10 , wherein the beads comprises an average diameter smaller than about 10 mm. 
     
     
         12 . The multicrystalline silicon brick of  claim 10 , wherein the beads comprises single crystalline silicon, multicrystalline silicon, silicon carbide, or combinations thereof. 
     
     
         13 . The multicrystalline silicon brick of  claim 12 , wherein an angle between a pole direction of a first single crystalline silicon bead and a normal to the bottom of the multicrystalline silicon ingot is different from an angle between a pole direction of a second single crystalline silicon bead and the normal to the bottom of the multicrystalline silicon ingot. 
     
     
         14 . A multicrystalline silicon brick, comprising
 a plurality of non-Σ grain boundaries; and   a plurality of Σ3 grain boundaries,   wherein a percentage of non-Σ grain boundaries is from about 60 to about 75 and a percentage of Σ3 grain boundaries is from about 12 to about 25.   
     
     
         15 . The multicrystalline silicon brick of  claim 14 , further comprising:
 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;   wherein a percentage of Σ3 grain boundaries is from about 12 to about 18 at the bottom portion.   
     
     
         16 . The multicrystalline silicon brick of  claim 14 , further comprising a preferred crystal orientation comprises {112}. 
     
     
         17 . The multicrystalline silicon brick of  claim 14 , wherein the percentage of Σ3 grain boundaries is lower than the percentage of the non-Σ grain boundaries and greater than other grain boundaries being more incoherent than the Σ3 grain boundaries. 
     
     
         18 . A multicrystalline silicon brick, comprising:
 a bottom portion starting from a bottom to a height of 100 mm;   a top portion starting from the height of 200 mm to a top; and   a nucleation promotion layer under the bottom portion, wherein the nucleation promotion layer comprises a plurality of beads.   
     
     
         19 . The multicrystalline silicon brick of  claim 18 , wherein a percentage of incoherent grain boundary in the bottom portion is greater than a percentage of incoherent grain boundary in the top portion. 
     
     
         20 . The multicrystalline silicon brick of  claim 18 , wherein a percentage of non-Σ grain boundaries is from about 60 to about 75 and a percentage of Σ3 grain boundaries is from about 12 to about 25.