Ab initio molecular dynamics and materials design for embedded phase-change memory

• Published in: npj computational materials Vol. 7; no. 1; pp. 1 - 8
• Main Authors: Sun, Liang, Zhou, Yu-Xing, Wang, Xu-Dong, Chen, Yu-Han, Deringer, Volker L., Mazzarello, Riccardo, Zhang, Wei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08.02.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/1005/1008; 639/301/1034/1035; Antimony; Atomic structure; Characterization and Evaluation of Materials; Chemistry and Materials Science; Computational Intelligence; Electronic structure; First principles; Germanium; Knowledge acquisition; Materials Science; Mathematical and Computational Engineering; Mathematical and Computational Physics; Mathematical Modeling and Industrial Mathematics; Molecular dynamics; Room temperature; Tellurium; Theoretical
• ISSN: 2057-3960; 2057-3960
• DOI: 10.1038/s41524-021-00496-7

The Ge 2 Sb 2 Te 5 alloy has served as the core material in phase-change memories with high switching speed and persistent storage capability at room temperature. However widely used, this composition is not suitable for embedded memories—for example, for automotive applications, which require very high working temperatures above 300 °C. Ge–Sb–Te alloys with higher Ge content, most prominently Ge 2 Sb 1 Te 2 (‘212’), have been studied as suitable alternatives, but their atomic structures and structure–property relationships have remained widely unexplored. Here, we report comprehensive first-principles simulations that give insight into those emerging materials, located on the compositional tie-line between Ge 2 Sb 1 Te 2 and elemental Ge, allowing for a direct comparison with the established Ge 2 Sb 2 Te 5 material. Electronic-structure computations and smooth overlap of atomic positions (SOAP) similarity analyses explain the role of excess Ge content in the amorphous phases. Together with energetic analyses, a compositional threshold is identified for the viability of a homogeneous amorphous phase (‘zero bit’), which is required for memory applications. Based on the acquired knowledge at the atomic scale, we provide a materials design strategy for high-performance embedded phase-change memories with balanced speed and stability, as well as potentially good cycling capability.