ZnSe molecular beam epitaxial growth on GaAs(110) substrates has been studied using reflection high-energy electron diffraction (RHEED), atomic force microscopy, and transmission electron microscopy. An atomically flat and low defect homoepitaxial buffer GaAs(110) was grown with high V/III ratio(⩾150)and at low growth temperature(∼430 °C).At the beginning of ZnSe growth on a GaAs(110) buffer epitaxial layer, RHEED oscillation was observed and no facet was seen on a pseudomorphic ZnSe(110) surface. Low defect ZnSe films (defect density⩽105 cm−2) were also obtained without the Zn preexposure process necessary for low defect ZnSe(001) growth. ©1997 American Institute of Physics.