Positron annihilation Doppler broadening measurements were conducted to characterize information of defects in 380 keV Xe+-implanted aluminum upon thermal annealing at temperatures ranging from 100 to 600 degrees C. The results suggest a broad distribution in the depth of vacancy-type defects in all the as-implanted samples. Meanwhile, with an increase in implantation dose the defect-rich region shifts toward the sample surface. It was found that increasing the annealing temperature triggers surface-directed migration and coalescence of vacancy and XenVm clusters in samples with implantation doses of 1E15 and 1E16 Xe+ cm(-2). In the sample implanted with a high dose of 1E17 Xe+ cm(-2), positron annihilation revealed a decomposition and even elimination of such defects under post-implantation annealing treatment. (C) 2013 Elsevier B.V. All rights reserved.