Crystallization Properties of the Ge sub(2)Sb sub(2)Te sub(5) Phase-Change Compound from Advanced Simulations

• Published in: Advanced functional materials 2015-10, Vol.25 (40), p.6407-6413
• Main Authors: Ronneberger, Ider, Zhang, Wei, Eshet, Hagai, Mazzarello, Riccardo
• Format: Article
• Language: English
• Subjects: Computer simulation; Crystal growth; Crystallization; Data storage; Molecular dynamics; Nuclei; Phase change; Simulation
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201500849

Ge sub(2)Sb sub(2)Te sub(5) (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 super(-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 Ge sub(2)Sb sub(2)Te sub(5) (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.