Ion irradiation with 130 keV Ge+ or 120 keV Sb+ has modified, by thermal spike effect, the local atomic arrangement in the structure of as-deposited sputtered amorphous GeTe and Ge2Sb2Te5 thin films. The changes in the local order have been analyzed by Raman and EXAFS spectroscopy. In addition the crystallization kinetic, measured by “in situ” time resolved reflectivity and optical microscope analysis, is found to be faster in the irradiated samples. The nucleation rate and the grain growth velocity are enhanced by a factor of about ten with respect to the unirradiated samples in the investigated temperature range ( 120°C -170°C).