Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

The role of vacancies and local distortions in the design of new phase-change materials

Nature Materials volume 6, pages 122–128 (2007)Cite this article

A Corrigendum to this article was published on 01 February 2007

Abstract

Phase-change materials are of tremendous technological importance ranging from optical data storage to electronic memories. Despite this interest, many fundamental properties of phase-change materials, such as the role of vacancies, remain poorly understood. ‘GeSbTe’-based phase-change materials contain vacancy concentrations around 10% in their metastable crystalline structure. By using density-functional theory, the origin of these vacancies has been clarified and we show that the most stable crystalline phases with rocksalt-like structures are characterized by large vacancy concentrations and local distortions. The ease by which vacancies are formed is explained by the need to annihilate energetically unfavourable antibonding Ge–Te and Sb–Te interactions in the highest occupied bands. Understanding how the interplay between vacancies and local distortions lowers the total energy helps to design novel phase-change materials as evidenced by new experimental data.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Rocksalt structure of Ge1Sb2Te4.
Figure 2: Defect formation energies.
Figure 3: COHP bonding analysis.
Figure 4: Pair correlation functions in the case of Ge vacancies.
Figure 5: XRD diffractograms of Ge1.5Sb2Te4, Ge2Sb2Te4 and Ge2Sb1Te4.
Figure 6: Optical properties and recrystallization behaviour.

Similar content being viewed by others

References

  1. El-Mellouhi, F., Mousseau, N. & Ordejon, P. Sampling the diffusion paths of a neutral vacancy in silicon with quantum mechanical calculations. Phys. Rev. B 70, 205202 (2004).

    Article  Google Scholar 

  2. Yamada, N. Erasable phase-change optical materials. Mater. Res. Soc. Bull. 21, 48–50 (1996).

    Article  CAS  Google Scholar 

  3. Ovshinsky, S. R. Reversible electrical switching phenomena in disordered structures. Phys. Rev. Lett. 21, 1450–1453 (1968).

    Article  Google Scholar 

  4. Wuttig, M. Phase-change materials—towards a universal memory? Nature Mater. 4, 265–266 (2005).

    Article  CAS  Google Scholar 

  5. Lankhorst, M., Ketelaars, B. & Wolters, R. Low-cost and nanoscale non-volatile memory concept for future silicon chips. Nature Mater. 4, 347–352 (2005).

    Article  CAS  Google Scholar 

  6. Kolobov, A. et al. Understanding the phase-change mechanism of rewritable optical media. Nature Mater. 3, 703–708 (2004).

    Article  CAS  Google Scholar 

  7. Wełnic, W. et al. Unraveling the interplay of local structure and physical properties in phase-change materials. Nature Mater. 5, 56–62 (2006).

    Article  Google Scholar 

  8. Matsunaga, T. & Yamada, N. Structural investigation of Ge1Sb2Te4: A high-speed phase-change material. Phys. Rev. B 69, 104111 (2004).

    Article  Google Scholar 

  9. Kooi, B., Groot, W. & de Hosson, J. In situ transmission electron microscopy study of the crystallization of Ge2Sb2Te5 . J. Appl. Phys. 95, 924–932 (2004).

    Article  CAS  Google Scholar 

  10. Abrikosov, N. & Danilova-Dobryakova, G. Study of the SbTe–GeTe phase diagram. Izv. Akad. Nauk. SSSR, Neorg. Mater. 1, 204–209 (1965).

    CAS  Google Scholar 

  11. Matsunaga, T., Kubota, Y. & Yamada, N. Structures of stable and metastable Ge2Sb2Te5, an intermetallic compound in the GeTe–Sb2Te3 pseudobinary systems. Acta Crystallogr. B 60, 685–691 (2004).

    Article  Google Scholar 

  12. Matsunaga, T. & Yamada, N. A study of highly symmetrical crystal structures, commonly seen in high speed phase change materials, using synchrotron radiation. Jpn J. Appl. Phys. 41, 1674–1678 (2002).

    Article  CAS  Google Scholar 

  13. Edwards, A. H. et al. Electronic structure of intrinsic defects in crystalline germanium telluride. Phys. Rev. B 73, 045210 (2006).

    Article  Google Scholar 

  14. Adler, D., Shur, M. & Ovshinsky, S. Threshold switching in chalcogenide-glass thin films. J. Appl. Phys. 51, 3289–3309 (1980).

    Article  CAS  Google Scholar 

  15. Pirovano, A., Lacaita, A., Benvenuti, A., Pellizzer, F. & Bez, R. Electronic switching in phase-change memories. IEEE Trans. Electron Devices 51, 452–459 (2004).

    Article  Google Scholar 

  16. Baranovskii, S. & Karpov, V. Localized electron states in glassy semiconductors (review). Sov. Phys. Semicond. 21, 1–10 (1987).

    Google Scholar 

  17. Matsunaga, T. et al. Single structure widely distributed in a GeTe–Sb2Te3 pseudobinary system: A rocksalt structure is retained by intrinsically containing an enormous number of vacancies within its crystal. Inorg. Chem. 45, 2235–2241 (2006).

    Article  CAS  Google Scholar 

  18. Shamoto, S. et al. Large displacement of germanium atoms in crystalline Ge2Sb2Te5 . Appl. Phys. Lett. 86, 081904 (2005).

    Article  Google Scholar 

  19. Glassey, W., Papoian, G. & Hoffmann, R. Total energy partitioning within a one-electron formalism: A Hamilton population study of surface-co interaction in the c(2×2)-CO/Ni (100) chemisorption system. J. Chem. Phys. 111, 893–910 (1999).

    Article  CAS  Google Scholar 

  20. Pearson, R. Absolute electronegativity and hardness: Application to inorganic chemistry. Inorg. Chem. 27, 734–740 (1988).

    Article  CAS  Google Scholar 

  21. Gaspard, J.-P. & Ceolin, R. Hume-Rothery rule in V–VI compounds. Solid State Commun. 84, 839–842 (1992).

    Article  CAS  Google Scholar 

  22. Peierls, R. Quantum Theory of Solids (Oxford Univ. Press, Oxford, 1956).

    Google Scholar 

  23. Gaspard, J.-P., Pellegatti, A., Marinelli, F. & Bichara, C. Peierls instabilities in covalent structures I. Electronic structure, cohesion and the Z=8−N rule. Phil. Mag. B 77, 727–744 (1998).

    Article  CAS  Google Scholar 

  24. Burdett, J. K. & McLarnan, T. J. A study of the arsenic, black phosphorus, and other structures derived from rock salt by bond-breaking processes. I. Structural enumeration. J. Chem. Phys. 75, 5764–5773 (1981).

    Article  CAS  Google Scholar 

  25. Burdett, J. K., Haaland, P. & McLarnan, T. J. A study of the arsenic, black phosphorus, and other structures derived from rock salt by bond-breaking processes. II. Band structure calculations and the importance of the gauche effect. J. Chem. Phys. 75, 5774–5781 (1981).

    Article  CAS  Google Scholar 

  26. Burdett, J. K. Chemical Bonds—A Dialog (Wiley, New York, 1997).

    Google Scholar 

  27. Miller, G. J. & Verkade, J. G. A pictorial approach to molecular orbital bonding in polymers: Non-mathematical but honest. J. Chem. Educ. 76, 428–433 (1999).

    Article  CAS  Google Scholar 

  28. Decker, A., Landrum, G. & Dronskowski, R. Structural and electronic peierls distortions in the elements (A): The crystal structure of tellurium. Z. Anorg. Allg. Chem. 628, 295–302 (2002).

    Article  CAS  Google Scholar 

  29. Kastner, M. Bonding bands, lone-pair bands, and impurity states in chalcogenide semiconductors. Phys. Rev. Lett. 28, 355–357 (1972).

    Article  CAS  Google Scholar 

  30. Gonzalez-Hernandez, J., Chao, B., Ovshinsky, S., Pawlik, D. & Gasiorowski, P. Crystallization studies of Ge:Sb:Te optical memory materials. Appl. Phys. Commun. 11, 557–581 (1992).

    CAS  Google Scholar 

  31. Lankhorst, M. Modelling glass transition temperatures of chalcogenide glasses. Applied to phase change optical recording materials. J. Non-Cryst. Solids 297, 210–219 (202).

  32. Zhou, G. Material aspects in phase change optical recording. Mater. Sci. Eng. A 304–306, 73–80 (2001).

    Article  Google Scholar 

  33. Borg, H., Lankhorst, M., Meinders, E. & Leibbrandt, W. Phase change media for high density optical recording. Mater. Res. Soc. Symp. Proc. 674, V1.2.1–10 (2001).

    Article  Google Scholar 

  34. Wuttig, M. et al. The quest for fast phase change materials. Mater. Res. Soc. Symp. Proc. 674, V1.8–16 (2001).

    Google Scholar 

  35. Gonze, X. et al. First-principles computation of material properties: the ABINIT software project. Comput. Mater. Sci. 25, 478–492 (2002).

    Article  Google Scholar 

  36. Goedecker, S. Fast radix 2, 3, 4 and 5 kernels for fast Fourier transformations on computers with overlapping multiply-add instructions. SIAM J. Sci. Comput. 18, 1605 (1997).

    Article  Google Scholar 

  37. Payne, M. C., Teter, M. P., Allan, D. C., Arias, T. A. & Joannopoulos, J. D. Iterative minimization techniques for ab initio total-energy calculations: molecular dynamics and conjugate gradients. Rev. Mod. Phys. 64, 1045–1097 (1992).

    Article  CAS  Google Scholar 

  38. Gonze, X. Towards a potential-based conjugate gradient algorithm for order-N self-consistent total energy calculations. Phys. Rev. B 54, 4383–4386 (1996).

    Article  CAS  Google Scholar 

  39. Fuchs, M. & Scheffler, M. Ab initio pseudopotentials for electronic structure calculations of poly-atomic systems using density-functional theory. Comput. Phys. Commun. 119, 67–98 (1999).

    Article  CAS  Google Scholar 

  40. Hamann, D. Generalized norm-conserving pseudopotentials. Phys. Rev. B 40, 2980–2987 (1989).

    Article  CAS  Google Scholar 

  41. Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).

    Article  CAS  Google Scholar 

  42. Andersen, O. K. Linear methods in band theory. Phys. Rev. B 12, 3060–3083 (1975).

    Article  CAS  Google Scholar 

  43. Skriver, H. The LMTO Method (Springer, Berlin, 1984).

    Book  Google Scholar 

  44. Andersen, O. The Electronic Structure of Complex Systems (Plenum, New York, 1984).

    Google Scholar 

  45. Andersen, O. K. & Jepsen, O. Explicit, first-principles tight-binding theory. Phys. Rev. Lett. 53, 2571–2574 (1984).

    Article  CAS  Google Scholar 

  46. Koringa, J. On the calculation of the energy of a bloch wave in a metal. Physica 13, 392–400 (1947).

    Article  Google Scholar 

  47. Kohn, W. & Rostoker, N. Solution of the Schrödinger equation in periodic lattices with an application to metallic lithium. Phys. Rev. 94, 1111–1120 (1954).

    Article  CAS  Google Scholar 

  48. von Barth, U. & Hedin, L. A local exchange-correlation potential for the spin polarized case. i. J. Phys. C: Solid State Phys. 5, 1629–1642 (1972).

    Article  CAS  Google Scholar 

  49. Hoffmann, R. Solids and Surfaces: A Chemist’s View of Bonding in Extended Structures (VCH, Weinheim, 1988).

    Book  Google Scholar 

  50. Dronskowski, R. Computational Chemistry of Solid State Materials (VCH, Weinheim, 2005).

    Book  Google Scholar 

Download references

Acknowledgements

We gratefully acknowledge support from the Deutsche Forschungsgemenischaft (Wu 243/11). We thank J. Neugebauer for fruitful discussions, Umicore (Liechtenstein) for the careful preparation of phase-change targets and M. Heidelmann for carrying out the static tester measurements. Furthermore, we thank the Rechenzentrum of the RWTH Aachen for providing computer time and technical support.

Author information

Authors and Affiliations

  1. I. Physikalisches Institut (IA), RWTH Aachen, Aachen, 52056, Germany

    Matthias Wuttig, Daniel Lüsebrink, Daniel Wamwangi & Wojciech Wełnic

  2. Institut für Anorganische Chemie der RWTH Aachen, 52056, Aachen, Germany

    Michael Gilleßen & Richard Dronskowski

Authors
  1. Matthias Wuttig
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Daniel Lüsebrink
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Daniel Wamwangi
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Wojciech Wełnic
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Michael Gilleßen
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Richard Dronskowski
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

D.L. carried out the plane-wave pseudopotential calculations (structural relaxation, formation energies); M.G. carried out the calculations for the quantum-chemical bonding analysis (COHP); D.W. carried out the experiments (XRD, ellipsometry, Kissinger analysis, recrystallization behaviour); M.W. initialized this research project and M.W., W.W. and R.D. carried out the analysis of the data.

Corresponding author

Correspondence to Matthias Wuttig.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary information (PDF 68 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Wuttig, M., Lüsebrink, D., Wamwangi, D. et al. The role of vacancies and local distortions in the design of new phase-change materials. Nature Mater 6, 122–128 (2007). https://doi.org/10.1038/nmat1807

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat1807

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing