Distortion of Local Atomic Structures in Amorphous Ge-Sb-Te Phase Change Materials

A. Hirata, T. Ichitsubo, P. F. Guan, T. Fujita, and M. W. Chen
Phys. Rev. Lett. 120, 205502 – Published 18 May 2018
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Abstract

The local atomic structures of amorphous Ge-Sb-Te phase-change materials have yet to be clarified and the rapid crystal-amorphous phase change resulting in distinct optical contrast is not well understood. We report the direct observation of local atomic structures in amorphous Ge2Sb2Te5 using “local” reverse Monte Carlo modeling dedicated to an angstrom-beam electron diffraction analysis. The results corroborated the existence of local structures with rocksalt crystal-like topology that were greatly distorted compared to the crystal symmetry. This distortion resulted in the breaking of ideal octahedral atomic environments, thereby forming local disordered structures that basically satisfied the overall amorphous structure factor. The crystal-like distorted octahedral structures could be the main building blocks in the formation of the overall amorphous structure of Ge-Sb-Te.

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  • Received 15 November 2017
  • Revised 20 January 2018

DOI:https://doi.org/10.1103/PhysRevLett.120.205502

© 2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

A. Hirata1,2,*, T. Ichitsubo3, P. F. Guan4, T. Fujita1, and M. W. Chen1,5

  • 1WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
  • 2Mathematics for Advanced Materials-OIL, AIST-Tohoku University, Sendai 980-8577, Japan
  • 3Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
  • 4Beijing Computational Science Research Center, Beijing 100084, People’s Republic of China
  • 5Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA

  • *Corresponding author. hirata@wpi-aimr.tohoku.ac.jp

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Issue

Vol. 120, Iss. 20 — 18 May 2018

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