The amorphous to crystal transition temperature has been measured in capped (10 nm SiO2) and uncapped Ge2Sb2Te5 (GST) films (20 nm thick) after irradiation with a 40 keV Ge+ in the range between 5 x 10(13) and 1 x 10(15) ions/cm(2). In the capped samples the crystallization temperature increases with fluence (15 degrees C at 1 x 10(15) ions/cm(2)). This effect is due to the doping of the GST layer with a few atom percent of recoiled O and Si atoms. The influence of the chemical species on the crystallization kinetics overcomes the effect of the ion-induced local rearrangement that instead decreases the transition temperature by a few degrees in the uncapped samples. Recoil implantation through the use of a thin capping layer may then be a viable alternative to the direct doping of chalcogenide thin films. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3527941] All rights reserved.