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

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.