Letter | Published:

An optoelectronic framework enabled by low-dimensional phase-change films

Nature volume 511, pages 206211 (10 July 2014) | Download Citation

Abstract

The development of materials whose refractive index can be optically transformed as desired, such as chalcogenide-based phase-change materials, has revolutionized the media and data storage industries by providing inexpensive, high-speed, portable and reliable platforms able to store vast quantities of data. Phase-change materials switch between two solid states—amorphous and crystalline—in response to a stimulus, such as heat, with an associated change in the physical properties of the material, including optical absorption, electrical conductance and Young’s modulus1,2,3,4,5. The initial applications of these materials (particularly the germanium antimony tellurium alloy Ge2Sb2Te5) exploited the reversible change in their optical properties in rewritable optical data storage technologies6,7. More recently, the change in their electrical conductivity has also been extensively studied in the development of non-volatile phase-change memories4,5. Here we show that by combining the optical and electronic property modulation of such materials, display and data visualization applications that go beyond data storage can be created. Using extremely thin phase-change materials and transparent conductors, we demonstrate electrically induced stable colour changes in both reflective and semi-transparent modes. Further, we show how a pixelated approach can be used in displays on both rigid and flexible films. This optoelectronic framework using low-dimensional phase-change materials has many likely applications, such as ultrafast, entirely solid-state displays with nanometre-scale pixels, semi-transparent ‘smart’ glasses, ‘smart’ contact lenses and artificial retina devices.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

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

  2. 2.

    , & Low-cost and nanoscale non-volatile memory concept for future silicon chips. Nature Mater. 4, 347–352 (2005)

  3. 3.

    ,& et al. Ultra-thin phase-change bridge memory device using GeSb. 2006 International Electron Devices Meeting (IEDM 2006) (2006)

  4. 4.

    et al. Phase-change random access memory: a scalable technology. IBM J. Res. Develop. 52, 465–479 (2008)

  5. 5.

    , , & Nanoscale phase change memory materials. Nanoscale 4, 4382–4392 (2012)

  6. 6.

    , , , & Tegesnau alloys for phase-change type optical disk memories. Jpn. J. Appl. Phys. 28, 1235–1240 (1989)

  7. 7.

    , , & Ultrafast reversible phase-change in GeSb films for erasable optical storage. Appl. Phys. Lett. 60, 3123–3125 (1992)

  8. 8.

    & Phase-change materials for rewriteable data storage. Nature Mater. 6, 824–832 (2007)

  9. 9.

    , , & Nanometre optical coatings based on strong interference effects in highly absorbing media. Nature Mater. 12, 20–24 (2013)

  10. 10.

    et al. Evolution of cell resistance, threshold voltage and crystallization temperature during cycling of line-cell phase-change random access memory. J. Appl. Phys. 110, 024505 (2011)

  11. 11.

    et al. Breaking the speed limits of phase-change memory. Science 336, 1566–1569 (2012)

  12. 12.

    et al. Engineering grains of Ge2Sb2Te5 for realizing fast-speed, low-power, and low-drift phase-change memories with further multilevel capabilities. 2012 International Electron Devices Meeting (IEDM 2012) (2012)

  13. 13.

    , , & Low-power switching of phase-change materials with carbon nanotube electrodes. Science 332, 568–570 (2011)

  14. 14.

    , & Highly scalable non-volatile and ultra-lowpower phase-change nanowire memory. Nature Nanotechnol. 2, 626–630 (2007)

  15. 15.

    & Structure of laser-crystallized Ge2Sb2+xTe5 sputtered thin films for use in optical memory. J. Appl. Phys. 88, 7020–7028 (2000)

  16. 16.

    , , , & The applications and technology of phase-only liquid crystal on silicon devices. J. Displ. Technol. 7, 112–119 (2011)

  17. 17.

    , & Accounting for interference, scattering, and electrode absorption to make accurate internal quantum efficiency measurements in organic and other thin solar cells. Adv. Mater. 22, 3293–3297 (2010)

  18. 18.

    , , & Local characterization and transformation of phase-change media by scanning thermal probes. J. Appl. Phys. 95, 2360–2364 (2004)

  19. 19.

    , & Nanoscale phase changes in crystalline Ge2Sb2Te5 films using scanning probe microscopes. J. Appl. Phys. 99, 024306 (2006)

  20. 20.

    , , , & Ultra-high-density phase-change storage and memory. Nature Mater. 5, 383–387 (2006)

  21. 21.

    , , , & Nanoscale phase transformation in Ge2Sb2Te5 using encapsulated scanning probes and retraction force microscopy. Rev. Sci. Instrum. 80, 083701 (2009)

  22. 22.

    et al. A single-pixel wireless contact lens display. J. Micromech. Microeng. 21, 125014 (2011)

  23. 23.

    , , & Tunable near-infrared and visible-light transmittance in nanocrystal-in-glass composites. Nature 500, 323–326 (2013)

  24. 24.

    Fighting blindness with microelectronics. Sci. Transl. Med. 5, 210ps216 (2013)

  25. 25.

    et al. Electrical wind force-driven and dislocation-templated amorphization in phase-change nanowires. Science 336, 1561–1566 (2012)

  26. 26.

    , , & Threshold switching and phase transition numerical models for phase change memory simulations. J. Appl. Phys. 103, 111101 (2008)

  27. 27.

    , , & Phase change memories have taken the field. 5th IEEE International Memory Workshop 13–16, (2013)

  28. 28.

    , , & A critical review of the present and future prospects for electronic paper. J. Soc. Inf. Displ. 19, 129–156 (2011)

  29. 29.

    Optical Properties of Thin Solid Films Ch. 4, 46–95 (Dover, 1991)

  30. 30.

    , & Modeling photocurrent action spectra of photovoltaic devices based on organic thin films. J. Appl. Phys. 86, 487–496 (1999)

Download references

Acknowledgements

We thank R. Taylor for scientific discussions related to optical spectroscopy measurements. We are grateful to M. Riede for discussions on the modelling aspects of our study. This research was supported by EPSRC via grant numbers EP/J018783/1, EP/J018694/1 and EP/J00541X/2 as well as the OUP John Fell Fund.

Author information

Affiliations

  1. Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK

    • Peiman Hosseini
    •  & Harish Bhaskaran
  2. College of Engineering, Mathematics and Physical Sciences, University of Exeter, Harrison Building, North Park Road, Exeter EX4 4QF, UK

    • C. David Wright

Authors

  1. Search for Peiman Hosseini in:

  2. Search for C. David Wright in:

  3. Search for Harish Bhaskaran in:

Contributions

All authors contributed substantially to this work. P.H. and H.B. conceived and designed the experiments. P.H. performed the experiments with input from H. B and C.D.W. All authors analysed the data. The manuscript was written by P.H. and H.B. with input from C.D.W.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Harish Bhaskaran.

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    This file contains Supplementary Text and Data 1-8, Supplementary Figures 1-6 and additional references.

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature13487

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.