We have investigated the effect of an MnAs buffer layer for the epitaxial growth of GaAs on MnZn ferrite substrates using reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), atomic force microscopy (AFM), and glazing incidence-angle X-ray diffraction (GIXD). The RHEED and XRD observation have shown that the crystal quality of the GuAs layer is dramatically improved by inserting the MnAs buffer layer in spite of its large lattice mismatch. AFM observation has revealed that the use of the MnAs buffer also leads to the improvement in surface morphology. The epitaxial relationship for GaAs/MnAs/ferrite structure turned out to be [1 1 1]GaAs//[0 0 0 1] MnAs// [1 1 1] ferrite and [1 1 (2) over bar] GaAs// [1 (1) over bar 0 0] MnAs// [1 1 (2) over bar] ferrite. These improvements can be attributed to the efficient relaxation of the lattice strain due to the softness of the MnAs metal bonding. (C) 2002 Elsevier Science B.V. All rights reserved.