Vacancy-mediated three-center four-electron bonds in GeTe-Sb2Te3 phase-change memory alloys

Alexander V. Kolobov, Paul Fons, Junji Tominaga, Stanford R. Ovshinsky

Research output: Contribution to journalArticlepeer-review

73 Citations (Scopus)


Although GeTe-Sb2Te3 (GST) alloys are widely used in data storage, many fundamental issues are still under debate. Here, we demonstrate that the presence of vacancies in the crystalline phase has far-reaching consequences, namely, a triad of twofold coordinated Te atoms with lone-pair electrons generated around the vacancy enables the formation of soft three-center four-electron bonds, whose properties provide an explanation for the unusual characteristics of GST, in particular, the increase in local disorder upon crystallization, the co-existence of a very fast switching rate with a large property contrast, the possibility of a solid-solid amorphization process that excludes conventional melting, and the drastic difference in crystallization behavior between GST and the ideal binary GeTe. Anisotropy of the three-center bonds may serve as an additional degree of freedom for information recording and provide a unified explanation for a variety of unique effects observed in lone-pair semiconductors.

Original languageEnglish
Article number165206
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number16
Publication statusPublished - 2013 Apr 22
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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