A closed, double-crucible has been proved to be very successful for preventing the deviation from the stoichiometric compositions of the melt in the process of ZnSe Bridgman growth, and to be necessary for preparing large twin-free ZnSe single crystals. Under the optimized growth conditions, ZnSe crystals have been grown from the source materials with different composition ratio (Zn/Se) of 1.03-0.98. Photoluminescence spectra show that the I-1(d); I-2 and I-1 emissions are dominant for sample is with Zn/Se = 1, Zn/Se > 1, and Zn/Se < 1, respectively. The measurement of Hall effect and C-V characteristics showed that the Zn/Se = 1 sample has a high resistivity, Zn/Se > 1 is low-resistivity, n-type, and Zn/Se < 1 is low-resistivity p-type. The highest carrier concentrations of n- and p-type ZnSe crystals are 8.8 x 10(17) cm(-3) and 1.8 x 10(17) cm(-3), respectively. These results show that low resistivity n- and p-type ZnSe single crystals can be successfully grown by changing the compositions of the starting materials.