Crystallization Properties of the Ge2Sb2Te5 Phase-Change Compound from Advanced Simulations

Abstract

Ge2Sb2Te5 (GST) is an important phase-change material used in optical and electronic memory devices. In this work, crystal growth of GST at 600 K is investigated by ab initio molecular dynamics. Simulations of two different crystallization processes are performed. In the first set of simulations, the growth of crystalline nuclei generated using the metadynamics method is studied. In the second set, models containing a planar amorphous-crystalline interface are considered and the crystallization at the interface is investigated. The extracted crystal growth velocities are in the range of 1 m s-1 in both cases and compare well with recent experimental measurements. It is also found that GST crystallizes into a disordered cubic phase in all the simulations. The crystallization properties of the phase-change material Ge2Sb2Te5 (GST) at high temperatures are investigated by advanced ab initio molecular dynamics simulations. The crystal growth processes from both a quasi-spherical nucleus and a planar amorphous-crystalline interface are considered. The obtained growth velocities are compatible with recent experiments. The simulations elucidate the fast crystal growth of the phase change GST compound at the atomistic level.