The development, during annealing, of periodic one-dimensional ripple structure has been investigated. The nanoscale ripple array was fabricated on silicon(001) crystal surface using focused ion beam (FIB). Annealing was performed isothermally in a flowing argon gas ambient at 670 degreesC. The morphology of the ripple before and after annealing was analyzed by use of atomic force microscope. The height of the ripple decreased after thermal annealing. Furthermore, after annealing, spikes of gallium and/or gallium-rich precipitate were also observed on the surface of the ripples and the FIB milled areas. (C) 2003 Elsevier B.V. All rights reserved.