Epitaxial growth characteristics of alpha-MnS on GaAs(l 0 0) substrates have been investigated by X-ray diffraction and double crystal rocking curve measurements. Growth of stoichiometric a-MnS films has been performed by hot-wall epitaxy using Mn and ZnS as a source of sulfur. The films on GaAs(I 0 0) at low substrate temperature exhibit multiphase crystal structures of zincblende and rocksalt, and the main structure is changed to rocksalt with increasing substrate temperature. Photoluminescence spectrum of the alpha-MnS epilayer at 5 K exhibits broad emission bands, which are attributed to Mn2+ ions. The band gap energy of the a-MnS epilayer at room temperature was also estimated to be about 3.3 eV by reflection. (c) 2006 Elsevier B.V. All rights reserved.