Growth characteristics of (1 0 0)CdZnTe layers in metalorganic vapor-phase epitaxy have been studied using dimethyl-zinc (DMZn), dimethylcadmium (DMCd), and diethyltelluride as precursors. Variations of Zn composition and layer growth rate were examined by changing the DMZn supply ratio from 0 (no DMZn) to 1.0(no DMCd). The growth rate of CdZnTe layers decreases monotonically with increase of the DMZn supply ratio. On the other hand, the Zn composition x of grown layers increases gradually up to x = 0.08 with an increase in the DMZn supply ratio from 0 to 0.8, beyond which the Zn composition increases abruptly to ZnTe. The abrupt transition of Zn composition is suppressed by increasing the VI/II ratio. The growth mechanism of CdZnTe layers was studied based on the growth characteristics of CdTe and ZnTe.