Sb-doped p-type ZnSe layers grown epitaxially on GaAs substrates by metalorganic vapor phase epitaxy (MOVPE) were investigated using deep-level transient spectroscopy (DLTS). All samples prepared at three different flow rate ratios of DMSe/DMZn (VI/II) have three hole traps. At VI/II = 2.45, which is a stoichiometric condition, the total concentration of the three deep traps is the lowest compared with the others. The trap at 0.46 eV is tentatively ascribed to be related to an Sb atom. The origin of a major trap at VI/II = 1.5 which has an activation energy of 0.62 eV is likely to be defects related to a Se vacancy. Although a major trap at VI/II = 3.27 has the same activation energy of 0.62 eV, its origin seems to be a Zn vacancy. (C) 2003 Elsevier B.V. All rights reserved.