In order to understand the basic characteristics of the gas-phase mass-transfer coefficient (k(g)) in a small silicon Czochralski (Cz) furnace, a very crude model was proposed and the results were correlated by the Sherwood number as a function of Reynolds number. It was confirmed that by installing a gas guide in the hot zone, the mass transfer coefficient was significantly enhanced. A set of global analyses of small Cz furnaces was conducted with different values of diffusivity of SiO in the gas phase (D-SiO) and of oxygen in the melt phase (DO) in order to elucidate which rate process controls the average oxygen concentration ([O](ave)) in the grown crystal. These simulations revealed that in these small Cz furnaces, [O](ave), is dependent on the gas phase mass transfer rate and melt flow patterns. A decrease in D-SiO causes an increase in [O](ave). An increase in D-O tends to increase [O](ave) slightly in most cases. (C) 2004 Elsevier B.V. All rights reserved.