The fabrication of submicrometer GaAs islands directly on Si substrates by droplet epitaxy is presented. Islands parameters, like density and size, are fully controlled through growth temperature and Ga coverage. The process is fully scalable and at low thermal budget, making these islands good candidates for local artificial substrates with lattice parameters, band alignment and crystalline quality as now required for the implementation of high quality III-As devices on Si. (C) 2010 Elsevier B.V. All rights reserved.