Effects of resonant bonding and structural distortion on the phase change properties of Sn2Sb2Se5

Min Ahn, Kwang Sik Jeong, Seungjong Park, Sungjin Park, Hoon Jung, Jeonghwa Han, Wonjun Yang, Dasol Kim, Hongsik Jeong, Mann Ho Cho

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


The phase-change characteristics of Sn2Sb2Se5 (SSS), a pseudo-binary chalcogenide material, were investigated for use in phase-change random access memory applications. Although an analysis of the power and phase-change speed using laser static test equipment showed superior phase-change properties, several instabilities existed during the phase-change process. It was also found that the difference in resistivity between the crystalline and amorphous structures was high, as compared to conventional Ge2Sb2Te5 (GST). The SSS material also required a higher set/reset switching power than GST in electrical pulse switching tests. Based on extended X-ray absorption fine structure measurements and ab initio calculations of the charge distribution, short and long bonds were not found to co-exist around the Sn atoms, unlike the Ge atoms in GST. This evidence leads to enhanced resonant bonding in SSS, which prevents the Sn atoms from participating in the Ge-like phase-change mechanism. While the Ge atoms in crystalline GST tend to occupy defective octahedral sites, the Sn atoms in SSS prefer a tightly bonded resonant bonding state with a six-fold geometry. This strong resonant bonding results in a lack of Peierls-like distortion in the SSS structure. As a result, the competition between Peierls-like distortion and resonant bonding significantly affects the phase-change characteristics such as the SSS instability and switching process.

Original languageEnglish
Pages (from-to)7820-7829
Number of pages10
JournalJournal of Materials Chemistry C
Issue number31
Publication statusPublished - 2017

Bibliographical note

Publisher Copyright:
© 2017 The Royal Society of Chemistry.

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Chemistry


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