NOVELTY - Controlling resistivity in the formation of silicon ingot (38) involves preparing compensated, upgraded metallurgical silicon feedstock (32) for being melted to form silicon melt, where feedstock has predominantly p-type semiconductor; assessing concentrations of boron and phosphorus (37); adding to feedstock, predetermined amount of element (34) selected from aluminum/gallium, where predetermined quantity is associated with assessed boron/phosphorus concentrations; melting feedstock and element to form molten silicon solution (36); and performing directional solidification of solution.    USE - For controlling resistivity in the formation of silicon ingot used as semiconductor ingot; in systems for forming large grain, multi-crystalline semiconductor ingot (claimed); in the manufacture of solar cells, solar wafers and similar product; in photovoltaic industry.    ADVANTAGE - The method effectively controls the resistivity in the formation of p-type silicon ingot; and permits the use of low-grade silicon feedstock. The method effectively controls the compensation effect of feedstock material; and increases the portion of p-type silicon material in ingot thereby increasing the yield of material. The method allows formation of silicon ingot directly within a silicon melt crucible. The solar wafers and solar cells comprising the silicon ingot exhibits improved performance/cost ratio.    DETAILED DESCRIPTION - Controlling resistivity in the formation of a silicon ingot (38) involves preparing a compensated, upgraded metallurgical silicon feedstock (32) for being melted to form a silicon melt, where the compensated, upgraded metallurgical silicon feedstock comprises a predominantly p-type semiconductor; assessing the concentrations of boron and phosphorus (37) in the compensated, upgraded metallurgical silicon feedstock; adding to the compensated, upgraded metallurgical silicon feedstock, a predetermined amount of an element (34) selected from aluminum and gallium, where the predetermined quantity of the element is associated with the assessed boron and phosphorus concentrations; melting the upgraded metallurgical silicon feedstock and the predetermined amount of an element selected from aluminum and gallium to form a molten silicon solution (36) including the predetermined amount of the element; and performing a directional solidification of the molten silicon solution for forming a silicon ingot and by virtue of adding the predetermined amount of the element, maintaining the homogeneity, the resistivity of the silicon ingot throughout the axial length of the silicon ingot. The compensated, upgraded metallurgical silicon feedstock comprises upgraded metallurgical silicon having an initial resistivity of approximately 0.15 to 5 Omega cm. The step of adding to the compensated feedstock further involves adding to the compensated, upgraded metallurgical silicon feedstock, a predetermined amount of aluminum in the event that the initial resistivity is approximately 0.15-0.5 Omega cm; or adding a predetermined amount of aluminum and phosphorus in the event that initial resistivity is approximately 0.4 Omega cm; or adding predetermined amount of gallium and/or a predetermined amount of phosphorus in the event that the initial resistivity is less than approximately 0.15-0.5 Omega cm. The step of performing a directional solidification of the molten silicon solution further involves yielding a silicon ingot comprising an uniform p-type doping distribution throughout the silicon ingot or comprising 100% p-type material with approximately 95% of the ingot having resistivity of 0.53-0.76 Omega cm. INDEPENDENT CLAIMS are included for the following:    (1) a semiconductor ingot comprising: a silicon material formed from a compensated, upgraded metallurgical grade silicon feedstock having been melted to form a silicon melt, where the compensated, upgraded metallurgical grade silicon feedstock comprises in a predominantly p-type semiconductor, a combination of boron and phosphorus, where the silicon material further contains predetermined amount of element selected from aluminum and gallium to form a molten silicon solution, where the predetermined amount of the group is added to maintain the silicon melt as a predominantly p-type silicon material throughout the formation of the silicon ingot. The silicon ingot is formed using a directional solidification of the molten silicon solution; and    (2) a system for forming a large grain, multi-crystalline semiconductor ingot comprising: a crucible for receiving and permitting preparation of compensated, upgraded metallurgical grade silicon feedstock for being melted to form a silicon melt, where the compensated, upgraded metallurgical grade silicon feedstock contains a predominantly p-type semiconductor; an assessment mechanism for assessing the concentrations of boron and phosphorus in the compensated, upgraded metallurgical grade silicon feedstock; an element-adding mechanism for adding to the compensated, upgraded metallurgical grade silicon feedstock, a predetermined amount of element selected from aluminum and gallium, where the predetermined quantity of element selected from aluminum and gallium is associated with the assessed boron and phosphorus concentration; a heating mechanism for melting the metallurgical grade silicon feedstock and the element selected from aluminum and gallium to form a molten silicon solution including the predetermined amount of element selected from aluminum and gallium; and a silicon solidification mechanism for performing a directional solidification of the molten silicon solution for forming a silicon ingot and, by virtue of adding a predetermined amount of element selected from aluminum and gallium, maintaining the homogeneity the resistivity of the silicon ingot throughout the silicon ingot.    DESCRIPTION OF DRAWING(S) - The figure shows schematic view of process for forming silicon ingot possessing all p-type silicon material.    Compensated p-type upgraded metallurgical (UM) silicon feedstock (32)    Group III element such as aluminum or gallium (34)    Molten silicon solution (36)    Phosphorus (37)    100% p-Type silicon ingot (38)