a method for producing a single crystal ingot includes steps of providing a first amount of polycrystalline material and a first amount of dopant material to form a first mixture having a first dopant concentration in a process furnace , increasing a temperature of the first mixture to provide a molten first mixture , providing a seed material to the molten first mixture , withdrawing the seed from the molten first mixture by a first distance to form a boule having a first length , providing a second amount of the polycrystalline material and a second amount of the dopant material to the molten first mixture to provide a molten second mixture having the first dopant concentration , withdrawing the first length of the boule from the molten second mixture by a second distance to form the boule having a second length , and removing the boule from the molten second mixture to form the single crystal ingot of uniform axial resistivity .