We have fabricated MnAs ferromagnetic nanoscaled dots on sulfur-passivated semiconductor substrates such as GaAs(001), GaAs(I I I)B, and InP(0 0 1) by low temperature molecular beam epitaxy (MBE). Atomic force microscopy (AFM) results reveal that the shape of MnAs dots depends on the surface energy of sulfur-passivated substrates. Extended X-ray absorption fine structure (EXAFS) and superconducting quantum interference device (SQUID) results suggest that MnAs dots on sulfur-passivated GaAs(0 0 1) are zb-type, while MnAs dots on sulfur-passivated GaAs(I I l)B and InP(0 0 1) are NiAs-type. We have found that the balance between substrate surface energy and lattice mismatch is essential to successfully fabricate zb-MnAs. (c) 2006 Elsevier B.V. All rights reserved.