These authors contributed equally to this work.
Structural insights into the formation and evolution of amorphous phase-change materials
Article first published online: 22 MAR 2013
Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
physica status solidi (b)
Special Issue: Disorder in Order: A special issue on amorphous materials honoring S. R. Elliott
Volume 250, Issue 5, pages 968–975, May 2013
How to Cite
Skelton, J. M., Loke, D., Lee, T. H. and Elliott, S. R. (2013), Structural insights into the formation and evolution of amorphous phase-change materials. Phys. Status Solidi B, 250: 968–975. doi: 10.1002/pssb.201248563
- Issue published online: 10 MAY 2013
- Article first published online: 22 MAR 2013
- Manuscript Accepted: 11 FEB 2013
- Manuscript Revised: 25 JAN 2013
- Manuscript Received: 22 NOV 2012
- Engineering and Physical Sciences Research Council (UK)
- ab initio molecular-dynamics;
- phase-change materials
Reduction of programming current is a major research goal in the development of phase-change random-access memory devices. The power-limiting step is the amorphization of the phase-change material (PCM), where a significant energy input is required to induce melting prior to amorphization. To address the challenge of reducing power consumption while retaining switching speed, a detailed understanding of the physics underpinning the amorphization process is required. As yet, little has been done to study the dynamics of the melt-quench process at the atomic level. In this article, we report a detailed study of the melting mechanism and kinetics, and the effect of quench rate on the amorphization process in the prototypical PCM Ge2Sb2Te5, using ab initio molecular-dynamics simulations. We also study the evolution of the amorphous phase under low-temperature annealing, shedding light on the structural changes, which may occur after amorphization at device operating temperatures. Our results give microscopic insight into the amorphization of PCMs, and should inform future work to understand and resolve important issues in device engineering.
Effect of quench rate on the structure of Ge2Sb2Te5: While quenching at −5 K ps−1 leads to successful amorphization (left), quenching at a slower −1 K ps−1 leads to crystallization as the temperature is lowered (right).