Crystallization of Ge2Sb2Te5 nanometric phase change material clusters made by gas-phase condensation

Abstract

The crystallization behavior of Ge2Sb2Te5 nanometric clusters was studied using X-ray diffraction with in situ annealing. Clusters were made using a sputtering gas-phase condensation source, which allowed for the growth of well-defined, contaminant-free, and isolated clusters. The average size for the clusters is 5.7 ± 1 nm. As-deposited amorphous clusters crystallize in the fcc cubic phase at 180 °C, while for thin films, the phase change temperature is 155 °C. This observation illustrates the scalability of the Ge2Sb2Te5 phase change from the amorphous to the cubic state in three-dimensionally confined systems in this size range. © 2012 American Institute of Physics.