Phase change in GeTe/Sb2Te3 superlattices: Formation of the vacancy-ordered metastable cubic structure via Ge migration

Chang Woo Lee, Jin Su Oh, Sun Ho Park, Hyeon Wook Lim, Da Sol Kim, Kyu Jin Cho, Cheol Woong Yang, Young Kyun Kwon, Mann Ho Cho

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1 Citation (Scopus)


Interfacial phase-change memory (iPCM), comprising alternating layers of two chalcogenide-based phase-change materials—Sb2Te3 (ST) and GeTe (GT)—has demonstrated outstanding performance in resistive memories. However, its comprehensive understanding is controversial. Herein, the phase-change characteristic of iPCM is identified using atomic scale imaging, X-ray diffraction, and chemical analysis with first-principles density functional theory (DFT) calculations. By inducing laser pulsing, the ST/GT superlattice structure in the low-resistance state tends to reversibly convert into the modified metastable face-centered cubic (fcc) GeSbTe structure in the high-resistance state. This transition is driven by Ge atom rearrangement to pre-existing vacancy layers and ordered vacancy-layer formation. DFT atomistic modeling shows that the resistance difference of 102 orders between low- and high-resistance states is a direct consequence of the intercalation of Ge atoms into the vacancy layer. These results provide insights into iPCM phase-change mechanisms and phase-change random access memory design with low energy and high speed.

Original languageEnglish
Article number154274
JournalApplied Surface Science
Publication statusPublished - 2022 Nov 15

Bibliographical note

Funding Information:
This research was supported by grants from the Nano Material Technology Development Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT, and Future Planning (NRF2016M3A7B4910398); the Ministry of Trade, Industry & Energy (MOTIE) in Korea (Project No. 10080625); the Government of Korea (MSIP) (No. 2021M3H4A1A03052566); the Korea Semiconductor Research Consortium (KSRC); and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2020M3F3A2A0108232413) through a project developing source technologies for future semiconductor devices. We would like to thank Editage ( for English language editing.

Publisher Copyright:
© 2022 Elsevier B.V.

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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