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:

Disorder-induced localization in crystalline phase-change materials

Nature Materials volume 10, pages 202–208 (2011)Cite this article

Subjects

Abstract

Localization of charge carriers in crystalline solids has been the subject of numerous investigations over more than half a century. Materials that show a metal–insulator transition without a structural change are therefore of interest. Mechanisms leading to metal–insulator transition include electron correlation (Mott transition) or disorder (Anderson localization), but a clear distinction is difficult. Here we report on a metal–insulator transition on increasing annealing temperature for a group of crystalline phase-change materials, where the metal–insulator transition is due to strong disorder usually associated only with amorphous solids. With pronounced disorder but weak electron correlation, these phase-change materials form an unparalleled quantum state of matter. Their universal electronic behaviour seems to be at the origin of the remarkable reproducibility of the resistance switching that is crucial to their applications in non-volatile-memory devices. Controlling the degree of disorder in crystalline phase-change materials might enable multilevel resistance states in upcoming storage devices.

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: Temperature dependence of the sheet resistance on annealing.
Figure 2: Universal changes of resistivity and its temperature dependence on annealing.
Figure 3: Resistivity of GeSb2Te4 films between 5 and 300 K.
Figure 4: Annealing-temperature dependence of the electrical-transport parameters of GeSb2Te4 films measured at room temperature.
Figure 5: The Mott criterion applied to GeSb2Te4.
Figure 6: Disorder in cubic GeSb2Te4 and the resulting MIT.

Similar content being viewed by others

References

  1. Kittel, Ch. Einführung in die Festkörperphysik 12 Auflage (R. Oldenbourg, 1999).

    Google Scholar 

  2. Mott, N. F. Conduction in non-crystalline systems IV. Anderson localization in a disordered lattice. Phil. Mag. 22, 7–29 (1970).

    Article  CAS  Google Scholar 

  3. Ioffe, A. F. & Regel, A. R. in Progress in Semiconductors Vol. 4 (ed. Gibson, A. F.) 237–291 (Heywood, 1960).

    Google Scholar 

  4. Rosenbaum, T. F., Andres, K., Thomas, G. A. & Bhatt, R. N. Sharp metal–insulator transition in a random solid. Phys. Rev. Lett. 45, 1723–1726 (1980).

    Article  CAS  Google Scholar 

  5. Abrahams, E., Anderson, P. W., Licciardello, D. C. & Ramakrishnan, T. V. Scaling theory of localization: Absence of quantum diffusion in two dimensions. Phys. Rev. Lett. 42, 673–676 (1979).

    Article  Google Scholar 

  6. Edwards, P. P., Ramakrishnan, T. V. & Rao, C. N. The metal–nonmetal transition: A global perspective. J. Phys. Chem. 99, 5228–5239 (1995).

    Article  CAS  Google Scholar 

  7. Mott, N. Review lecture: Metal–insulator transitions. Proc. R. Soc. Lond. A 382, 1–24 (1982).

    Article  CAS  Google Scholar 

  8. Anderson, P. W. Absence of diffusion in certain random lattices. Phys. Rev. 109, 1492–1505 (1958).

    Article  CAS  Google Scholar 

  9. Shklovskii, B. I. & Efros, A. L. Electronic Properties of Doped Semiconductors (Springer, 1984).

    Book  Google Scholar 

  10. Gaymann, A., Geserich, H. P. & Löhneysen, H. v. Temperature dependence of the far-infrared reflectance spectra of Si:P near the metal–insulator transition. Phys. Rev. B 52, 16486–16493 (1995).

    Article  CAS  Google Scholar 

  11. Alexander, M. N. & Holcomb, D. F. Semiconductor-to-metal transition in n-type group IV semiconductors. Rev. Mod. Phys. 40, 815–829 (1968).

    Article  CAS  Google Scholar 

  12. Belitz, D. & Kirkpatrick, T. R. The Anderson–Mott transition. Rev. Mod. Phys. 66, 261–380 (1994).

    Article  CAS  Google Scholar 

  13. Lee, P. A. & Ramakrishnan, T. V. Disordered electronic systems. Rev. Mod. Phys. 57, 287–337 (1985).

    CAS  Google Scholar 

  14. Baranovski, S. (ed.) Charge Transport in Disordered Solids with Applications in Electronics (John Wiley, 2006).

  15. Friedrich, I., Weidenhof, V., Njoroge, W., Franz, P. & Wuttig, M. Structural transformations of Ge2Sb2Te5 films studied by electrical resistance measurements. J. Appl. Phys. 87, 4130–4134 (2000).

    Article  CAS  Google Scholar 

  16. Nirschl, T. et al. Write strategies for 2 and 4-bit multi-level phase-change memory. Tech. Dig. Int. Electron Devices Meet. 461–464 (2007).

  17. Bruns, G. et al. Nanosecond switching in GeTe phase change memory cells. Appl. Phys. Lett. 95, 043108 (2009).

    Article  Google Scholar 

  18. Wang, W. J. et al. Fast phase transitions induced by picosecond electrical pulses on phase change memory cells. Appl. Phys. Lett. 93, 043121 (2008).

    Article  Google Scholar 

  19. Wuttig, M. & Yamada, N. Phase-change materials for rewritable data storage. Nature Mater. 6, 824–832 (2007).

    Article  CAS  Google Scholar 

  20. Bahl, S. K. & Chopra, K. L. Amorphous versus crystalline GeTe films. II. Optical properties. J. Appl. Phys. 40, 4940–4947 (1969).

    Article  CAS  Google Scholar 

  21. Njoroge, W. K., Wöltgens, H-W. & Wuttig, M. Density changes upon crystallization of Ge2Sb2.04Te4.74 films. J. Vac. Sci. Technol. A 20, 230–233 (2002).

    Article  CAS  Google Scholar 

  22. Kato, T. & Tanaka, K. Electronic properties of amorphous and crystalline Ge2Sb2Te5 films. Jpn. J. Appl. Phys. 44, 7340–7344 (2005).

    Article  CAS  Google Scholar 

  23. Lee, B-S. et al. Investigation of the optical and electronic properties of Ge2Sb2Te5 phase change material in its amorphous, cubic, and hexagonal phases. J. Appl. Phys. 97, 093509 (2005).

    Article  Google Scholar 

  24. Zhang, T. et al. Effect of structural transformation on the electrical properties for Ge1Sb2Te4 thin film. Thin Solid Films 516, 42–46 (2007).

    Article  CAS  Google Scholar 

  25. Prokhorov, E., Trapaga, G. & González-Hernández, J. Structural and electrical properties of Ge1Sb2Te4 face centered cubic phase. J. Appl. Phys. 104, 103712 (2008).

    Article  Google Scholar 

  26. Mott, N. F. Conduction in glasses containing transition metal ions. J. Non-Cryst. Solids 1, 1–17 (1968).

    Article  CAS  Google Scholar 

  27. Mott, N. F. Electrons in disordered structures. Adv. Phys. 16, 49–144 (1967).

    Article  CAS  Google Scholar 

  28. Overhof, H. & Thomas, P. Electronic Transport in Hydrogenated Amorphous Semiconductors (Springer, 1989).

    Book  Google Scholar 

  29. Gunnarsson, O., Calandra, M. & Han, J. E. Colloquium: Saturation of electrical resistivity. Rev. Mod. Phys. 75, 1085–1099 (2003).

    Article  Google Scholar 

  30. Klein, A. et al. Changes in electronic structure and chemical bonding upon crystallization of the phase change material GeSb2Te4 . Phys. Rev. Lett. 100, 016402 (2008).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  32. Wuttig, M. et al. The role of vacancies and local distortions in the design of new phase-change materials. Nature Mater. 6, 122–128 (2007).

    Article  CAS  Google Scholar 

  33. Shportko, K. et al. Resonant bonding in crystalline phase-change materials. Nature Mater. 7, 653–658 (2008).

    Article  CAS  Google Scholar 

  34. Lencer, D. et al. A map for phase-change materials. Nature Mater. 7, 972–977 (2008).

    Article  CAS  Google Scholar 

  35. Littlewood, P. B. Dielectric-constant of cubic IV–VI compounds. J. Phys. C 12, 4459–4468 (1979).

    Article  CAS  Google Scholar 

  36. Abrahams, E., Kravchenko, S. V. & Sarachik, M. P. Colloquium: Metallic behaviour and related phenomena in two dimensions. Rev. Mod. Phys 7 3, 251–266 (2001).

    Article  Google Scholar 

  37. Matsunaga, T. & Yamada, N. Structural investigation of GeSb2Te4: A high-speed phase-change material. Phys. Rev. B 69, 104111 (2004).

    Article  Google Scholar 

  38. Dynes, R. C. & Garno, J. P. Metal–insulator transition in granular aluminum. Phys. Rev. Lett. 46, 137–140 (1981).

    Article  CAS  Google Scholar 

  39. Edwards, P. P. & Sienko, M. J. Universality aspects of the metal–nonmetal transition in condensed media. Phys. Rev. B 17, 2575–2581 (1978).

    Article  CAS  Google Scholar 

  40. DaSilva, J. L., Walsh, A. & Lee, H. Insights into the structure of the stable and metastable (GeTe)m(Sb2Te3)n compounds. Phys. Rev. B 78, 224111 (2008).

    Article  Google Scholar 

  41. Kim, J. J. et al. Electronic structure of amorphous and crystalline (GeTe)1−x(Sb2Te3)x investigated using hard X-ray photoemission spectroscopy. Phys. Rev. B 76, 115124 (2007).

    Article  Google Scholar 

  42. Thouless, D. Anderson localization in the seventies and beyond. Int. J. Mod. Phys. B 24, 1507–1525 (2010).

    Article  CAS  Google Scholar 

  43. Mott, N. F. The transition to the metallic state. Phil. Mag. 6, 287–309 (1961).

    Article  CAS  Google Scholar 

  44. Mooij, J. H. Electrical conduction in concentrated disordered transition metal alloys. Phys. Status Solidi A 17, 521–530 (1973).

    Article  CAS  Google Scholar 

  45. Tsuei, C. C. Nonuniversality of the Mooij correlation—the temperature coefficient of electrical resistivity of disordered metals. Phys. Rev. Lett. 57, 1943–1946 (1986).

    Article  CAS  Google Scholar 

  46. van der Pauw, L. J. A method of measuring specific resistivity and Hall effect of discs of arbitrary shape. Philips Res. Rep. 13, 1–9 (1958).

    Google Scholar 

  47. Goldak, J., Barrett, C. S., Innes, D. & Youdelis, W. Structure of alpha GeTe. J. Chem. Phys. 44, 3323–3325 (1966).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

We would like to thank F. Evers, A. Kapitulnik, S. Kievelson, T. Geballe, B. Shklovskii and B. Spivak for discussions. Financial support by the Deutsche Forschungsgemeinschaft (Wu243/17), the Seed Funds of the Faculty for Mathematics, Informatics, and the Natural Sciences at RWTH Aachen and the Alexander von Humboldt Foundation (for T.S.) is acknowledged.

Author information

Authors and Affiliations

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

    T. Siegrist, P. Jost, H. Volker, M. Woda, P. Merkelbach, C. Schlockermann & M. Wuttig

  2. Department of Chemical and Biomedical Engineering, Florida State University, Tallahassee, Florida 32310, USA

    T. Siegrist

  3. JARA-FIT, RWTH Aachen University, I. Physikalisches Institut (IA), 52056 Aachen, Germany

    M. Wuttig

Authors
  1. T. Siegrist
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. P. Jost
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. H. Volker
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. M. Woda
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. P. Merkelbach
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. C. Schlockermann
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. M. Wuttig
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

M. Woda and P.M. prepared the samples. Measurements were carried out by M. Woda (high-temperature R(T)), P.M. (X-ray) and H.V. (low-temperature R(T), Hall effect). The custom-designed Hall set-up was developed by C.S. Analysis of the data was carried out by P.J., and the paper was written by T.S. and M. Wuttig, and P.J. composed the Supplementary Information. The project was initiated by M. Wuttig.

Corresponding author

Correspondence to M. Wuttig.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1402 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Siegrist, T., Jost, P., Volker, H. et al. Disorder-induced localization in crystalline phase-change materials. Nature Mater 10, 202–208 (2011). https://doi.org/10.1038/nmat2934

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat2934

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