heating a crucible comprising a first charge of silicon to cause a first silicon melt to form in the crucible;

contacting a silicon seed crystal with the first silicon melt, the first silicon melt having a first impurity profile;

withdrawing the silicon seed crystal to grow a first single crystal silicon ingot;

slicing a first plurality of silicon substrates from the first single crystal silicon ingot;

contacting a front surface of a silicon substrate of the first plurality of silicon substrates with a first silicon-containing gas, the first silicon-containing gas decomposing to form a first epitaxial silicon layer on the silicon substrate to form a first epitaxial wafer;

imaging the first epitaxial wafer by infrared depolarization to determine a first infrared depolarization parameter;

heating a crucible comprising a second charge of silicon to cause a second silicon melt to form in the crucible;

contacting a silicon seed crystal with the second silicon melt, the second silicon melt having a second impurity profile, the first impurity profile of the first melt being different than the second impurity profile of the second melt;

withdrawing the silicon seed crystal to grow a second single crystal silicon ingot;

slicing a second plurality of silicon substrates from the second single crystal silicon ingot;

contacting a front surface of a silicon substrate of the second plurality of silicon substrates with a second silicon-containing gas, the second silicon-containing gas decomposing to form a second epitaxial silicon layer on the silicon substrate to form a second epitaxial wafer;

imaging the second epitaxial wafer by infrared depolarization to determine a second infrared depolarization parameter; and

determining suitability of the first impurity profile and the second impurity profile to produce substrates for epitaxy based on the first and second infrared depolarization parameters, wherein the crucible in which the first silicon melt forms is part of a crystal puller apparatus, the crystal puller apparatus being the same or different from a crystal puller apparatus which comprises the crucible in which the second silicon melt forms, and wherein the silicon seed crystal that contacts the first silicon melt and the silicon seed crystal that contacts the second silicon melt are the same or different silicon seed crystals.