Graphite hot components were improved in a Czochralski-type puller and carbon concentrations were reduce in silicon crystals to 3 x 10(14) cm-3 at a solidified fraction of 5% and to 6 x 10(14) cm-3 at 80%. The improvements include a means to exhaust carbon monoxide gas generated from the graphite heat shield, silicon carbide coatings on the graphite heater, crucible, suscepter, and purge tube. It was found that the graphite heat shield is an important source of carbon, and that carbon monoxide evolution from the melt surface is an important purification mechanism in the Czochralski silicon growth process in addition to the segregation phenomenon of carbon.