We have studied the influence of the surface stoichiometry of the (001)GaAs surface (beta(2 x 4)As, (i x 3)Te, and (4 x 2)Ga) on the growth mode and defect generation in MBE-grown ZnSe, For the beta(2 x 4)As and (i x 3)Te surfaces, no interfacial compounds are formed and the observed stacking faults are not related to the interface. The stacking fault densities and the critical thicknesses are comparable for both the beta(2 x 4)As and (i x 3)Te. For the ZnSe layers grown onto a(4 x 2)Ga surface, a different behavior is observed. Ga-related precipitates are formed near the interface. For thicknesses below 100 nm the misfit is partially relaxed by dislocations generated to accommodate the precipitates. Few stacking faults are generated and are seen to be nucleated at the precipitates. (C) 1999 Elsevier Science B.V. All rights reserved.