Phase Change via Intermediary Metastable Local Structure of Ge Atoms in Ge2Sb2Te5Nanowires during Electrical Switching

Min Ahn, Jin Su Oh, Dambi Park, Hoon Jung, Sungjin Park, Kwangsik Jeong, Dasol Kim, Nark Eon Sung, Kug Seung Lee, Cheol Woong Yang, Mann Ho Cho

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


In this study, local structural changes induced by electrical SET/RESET operations in single-crystalline Ge2Sb2Te5 (GST) nanowires (NWs) fabricated via the vapor-liquid-solid method have been investigated using nanoscale extended X-ray absorption fine structure experiments. Under the aforementioned situation, GST NWs were observed to exhibit significant alterations in morphology and composition induced by atomic migration without undergoing any structural phase transition. As the characteristics of atomic migration during memory switching operation is very different from those corresponding to thin GST film-based device switching, the modulation of the local structure during the former process has not yet been clearly understood. In order to analyze the local structure of GST NWs, special nanoscale X-ray absorption fine structure (XAFS) analysis configurations were prepared, which enabled XAFS measurements over the scale of a few hundred nanometers. The results obtained from the nanoscale XAFS experiment suggested the simultaneous formation of metastable amorphous-like tetrahedral and FCC-like structures in GST NWs during RESET operations as a consequence of atomic migration, which enabled repeating SET/RESET operations in NWs. Finally, the results obtained from the nanoscale XAFS experiments were confirmed via Raman and transmission electron microscopy analysis, thus verifying the possible phase-change process between the FCC-like and hexagonal closed packed structure through an intermediary metastable local structure in asymmetrical NW structures with low thermal conduction.

Original languageEnglish
Pages (from-to)2418-2428
Number of pages11
JournalACS Applied Electronic Materials
Issue number8
Publication statusPublished - 2020 Aug 25

Bibliographical note

Funding Information:
We gratefully acknowledge the financial support provided by the Ministry of Trade, Industry & Energy (MOTIE) in Korea (project no. 10045360) and the Korea Semiconductor Research Consortium (KSRC) through a project for developing source technology for future semiconductor devices, and the Nano·Material Technology Development Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, and Future Planning (MSIP) (grant no. 2016M3A7B4910398). In addition, we acknowledge the 8C beam line in the Pohang accelerator laboratory for their experimental help.

Publisher Copyright:
Copyright © 2020 American Chemical Society.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Electrochemistry


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