The origins of metal impurities in Czochralski-grown single-crystal silicon were investigated in order to develop crystals with improved radial impurity homogeneity. The radial metallic impurity distribution in silicon crystals was evaluated by means of minority carrier recombination lifetime. The crystal circumference was found to be an area of degraded lifetime. A quantitative analysis of radial impurity distribution in silicon was carried out using deep level transient spectroscopy techniques. Iron was the predominant impurity detected on the circumference of the crystal. The radial distribution of iron impurity concentration showed good correlation with calculated results. An experimental technique was developed which allowed us to isolate the influence of the graphite parts of the Czochralski furnace as a contamination source during high-temperature processing; Commercially available graphite materials of different purity levels, both with and without silicon carbide coatings, were evaluated. It was confirmed that the graphite furnace parts play a role in determining the radial impurity distribution profile.