In this study, GeMn thin films were fabricated by implantation of Mn ions at room temperature. Post-annealing was performed using 2 MeV of He+ ion irradiation. The recrystallization phenomena of the GeMn thin films were analyzed by Raman scattering. High-resolution transmission electron microscopy was also used to characterize the recrystallization process before and after ion beam annealing. A structure phase transition-like behavior of the recrystallization process of GeMn thin films was observed in the Raman spectra. (C) 2015 Elsevier B.V. All rights reserved.