Two hundred millimeter single crystals with various oxygen concentrations are grown in the cusp-magnetic Czochralski method, and the effects of heating condition (which corresponds to different crucible positions with the fixed heater), the seed rotation and argon flow rate on the oxygen concentration and its distribution in the crystal are experimentally investigated. The oxygen concentration decreases with increasing melt level because of lower temperature at the bottom of the crucible. The oxygen radial gradients are less than 2%. Oxygen concentration decreases as the argon flow rate increases. Large single crystal with the extremely low oxygen concentrations is possible in the Czochralski method. (c) 2004 Elsevier B.V. All rights reserved.