Czochralski silicon (CZ-Si) crystals were grown using different V/G ratios (V: growth rate, G: axial temperature gradient) of 0.23 mm(2)/degreesC min and 0.38 mm(2)/degreesC min, respectively, while the axial temperature gradient near the melt-crystal interface was measured by a thermocouple of differential type developed recently. Defects in the grown crystals were systematically investigated by multi-chroic infrared light scattering tomography (MC-IR-LST) to experimentally identify the relationship between the characteristics of defects in the CZ-Si crystals and the V/G ratios. High defect density was detected in the CZ-Si crystal grown under a V/G ratio of 0.38 mm(2)/degreesC min, in which the density distribution of defects along the crystal growth direction obviously fluctuated. The highest defect density existed in the middle region of the crystal while lower defect density was seen in the top area. No defect was detectable by the MC-IR-LST system in the CZ-Si crystal grown under the V/G ratio of 0.23 mm(2)/degreesC min, The type of grown-in defects in the CZ-Si crystal grown under the V/G ratio of 0.38 mm(2)/degreesC min was the vacancy agglomeration based on the result of photoluminescence detection and the V/G ratio used for crystal growth. (C) 2002 Published by Elsevier Science B.V.