GaSb(1 0 0) samples were irradiated with 60 keV Ar + -ions at normal incidence for fluences in the range of 7 × 10 16 to 3 × 10 18 ions cm -2 at room temperature, showing gradual evolution of a porous surface layer containing interconnected nanofibers. In particular, fluence dependent formation of patches on the nanoporous layer is observed by scanning electron microscopy. Combined results of grazing incidence x-ray diffraction and transmission electron microscopy reveal the presence of nanocrystallites in the porous structures. Compositional analysis by x-ray photoelectron spectroscopy indicates the development of oxide phases, mainly Ga 2 O 3 and Sb 2 O 3 where the former increases with fluence. We have proposed a model addressing a competition between ion-induced-defect driven growth of the nanoporous layer and redeposition of sputtered target atoms on the growing layer. © 2014 Elsevier B.V.