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Structure of Amorphous Ge-Sb-Te Solids

  • Stephen R. Elliott

Abstract

This chapter reviews what is currently known about the atomic structure of Ge-Sb-Te phase-change materials in the amorphous phase. An introduction is first given to aspects of structural order in amorphous solids at different length scales, and brief reviews of experimental techniques for structure determination and of computer-simulation methods are outlined. A discussion is then given of the available experimental data on the structure of Ge-Sb-Te amorphous solids, primarily Ge2Sb2Te5, together with the results of various computer-simulation studies of these materials.

Keywords

Pair Distribution Function EXAFS Data Reverse Monte Carlo First Sharp Diffraction Peak Wrong Bond 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. [4.1]
    Elliott, S.R., Physics of Amorphous Materials, 2nd ed. (Longman: 1990)Google Scholar
  2. [4.2]
    Hegedüs, J. and Elliott, S.R.: Microscopic origin of the fast crystallization ability of Ge–Sb–Te phase-change memory materials. Nature Materials 7, 399-405 (2008)CrossRefGoogle Scholar
  3. [4.3]
    McGreevy, R.L. and Pusztai, L.: Reverse Monte Carlo Simulation: A new technique for the determination of disordered structures. Mol. Simul. 1, 359-367 (1988)CrossRefGoogle Scholar
  4. [4.4]
    Kohara, S., Kato, K., Kimura, S., Tanaka, H., Usuki, T., Suzuya, K., Tanaka, H., Moritomo, Y., Matsunaga, T., Yamada, N., Tanaka, Y., Suematsu, H. and Takata, M.: Structural basis for the fast phase change of Ge2Sb2Te5: Ring statistics analogy between the crystal and amorphous states. Appl. Phys. Lett., 89, 201910(1-3) (2006)CrossRefGoogle Scholar
  5. [4.5]
    Kohara, S., Kimura, S., Tanada, H., Yasuda, N., Fukuyama, Y., Murayama, H., Kim, J., Takata, M., Kato, K., Tanaka, Y., Usuki, T., Suzuyu, K., Tanaka, H., Moritomo, Y., Matsunaga, T., Kojima, R. and Yamada, N.: Structural basis for fast phase change of DVD-RAM -Topological order in the amorphous phase. Proc. European Phase Change and Ovonic Science Symposium 2007, http://www.epcos.org/library/Library2007.htm
  6. [4.6]
    Jovari, P., Kabau, I., Steiner, J., Beuneu, B., Schöps, A. and Webb, A.: ‘Wrong bonds’ in sputtered amorphous Ge2Sb2Te5. J. Phys. Cond. Matter 19, 335212 (9pp) (2007)CrossRefGoogle Scholar
  7. [4.7]
    Wuttig, M., Lüsebrink, D., Wamwangi, D., Welnic, W., Gillessen, M. and Dronskowski, R.: The role of vacancies and local distortions in the design of new phase-change materials. Nature Mater. 6, 122-U7 (2007)CrossRefGoogle Scholar
  8. [4.8]
    Baker, D.A., Paesler, M.A., Lucovsky, G. and Taylor, P.C.: EXAFS study of amorphous Ge2Sb2Te5. J. Non-Cryst. Sol. 352, 1621-1623 (2006a)CrossRefGoogle Scholar
  9. [4.9]
    Baker, D.A., Paesler, M.A., Lucovsky, G., Agarwal, S.C. and Taylor, P.C.: Application of bond constraint theory to the switchable optical memory material Ge2Sb2Te5. Phys. Rev. Lett. 96, 255501(1-3) (2006b)Google Scholar
  10. [4.10]
    Paesler, M.A., Baker, D.A., Lucovsky, G., Edwards, A.E. and Taylor, P.C.: EXAFS study of local order in the amorphous chalcogenide semiconductor Ge2Sb2Te5. J. Optoel. Adv. Mater. 8, 2039-2043 (2006)Google Scholar
  11. [4.11]
    Jovari, P., Kaban, I., Steiner, J., Beuneu, B., Schöps, A. and Webb, M.A.: Local order in amorphous Ge2Sb2Te5 and GeSb2Te4. Phys. Rev. B77, 035202(1-6) (2008)CrossRefGoogle Scholar
  12. [4.12]
    Arai, T., Sato, M and Umesaki, N.: Structural change of crystalline and amorphous-Ge2Sb2Te5 by reverse Monte Carlo analysis of x-ray diffraction data and extended x-ray absorption fine structure data. J. Phys. Cond. Matter. 19, 335213 (11pp) (2007)Google Scholar
  13. [4.13]
    Kolobov, A.V., Fons, P., Frenkel, A.I., Ankudinov, A.L., Tominaga, J. and Uruga, T.: Understanding the phase-change mechanism of rewritable optical media. Nature Mater. 3, 703-708 (2004)CrossRefGoogle Scholar
  14. [4.14]
    Klein, A., Dieker, H., Späth, B., Fons, P., Kolobov, A., Steiner, C. and Wuttig, M.: Changes in electronic structure and chemical bonding upon crystallization of the phase change material GeSb2Te4. Phys. Rev. Lett. 100, 016402(1-4) (2008)CrossRefGoogle Scholar
  15. [4.15]
    Caravati, S., Bernasconi, M., Kuhne, T.D., Krack, M. and Parrinello M.: Coexistence of tetrahedral- and octahedral-like sites in amorphous phase change materials. Appl. Phys. Lett., 91, 171906(1-3) (2007)CrossRefGoogle Scholar
  16. [4.16]
    Kühne, T.D., Krack, M., Mohamed, F.R. and Parrinello, M.: Efficient and accurate Car-Parrinello-like approach to Born-Oppenheimer molecular dynamics. Phys. Rev. Lett. 98, 066401(1-4) (2007); http://cp2k.berlios.de CrossRefGoogle Scholar
  17. [4.17]
    Errington, J.R. and Debenedetti, P.G., Relationship between structural order and the anomalies of liquid water. Nature 409, 318-321 (2001)CrossRefGoogle Scholar
  18. [4.18]
    Bichara, C., Johnson, M. and Gaspard, J.P.: Octahedral structure of liquid GeSb2Te4 alloy: First-principles molecular dynamics study. Phys. Rev. B75, 060201(R)(1-4) (2007)CrossRefGoogle Scholar
  19. [4.19]
    Akola, J. and Jones, R.O.: Structural phase transitions on the nanoscale: The crucial pattern in the phase-change materials Ge2Sb2Te5 and GeTe. Phys. Rev. B76, 235201 (10 pages) (2007); http://www.cpmd.org CrossRefGoogle Scholar
  20. [4.20]
    Kresse, G. and Hafner, J.: Ab initio molecular-dynamics for liquid-metals. Phys. Rev. B47, 558-561 (1993)CrossRefGoogle Scholar
  21. [4.21]
    Segall, M.D., Lindan, P.J.D., Probert, M.J., Pickard, C.J., Hasnip, P.J., Clarke, S.J. and Payne, M.C.: First-principles simulation: ideas, illustrations and the CASTEP code. J. Phys. Cond. Matt. 14, 2717-2744 (2002)CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Department of ChemistryUniversity of CambridgeCambridgeUK

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