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Van der Waals interfacial bonding and intermixing in GeTe-Sb2Te3-based superlattices

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Abstract

Interfacial phase change memory (iPCM) based on GeTe and Sb2Te3 superlattices (SLs) is an emerging contender for non-volatile data storage applications. A detailed knowledge of the atomic structure of these materials is crucial for further development of SLs and for a better understanding of the resistivity switching characteristics of iPCM devices. In this work, crystalline GeTe-Sb2Te3-based SLs, produced by pulsed laser deposition onto a Si(111) substrate at temperatures lower than in previous studies, are analyzed by advanced scanning transmission electron microscopy. The results reveal the formation of Ge-rich Ge(x+y)Sb(2–y)Tez building blocks with specific numbers of ordered Ge cation layers (between 1 and 5) and disordered cation layers (4) for z = 6–10, as well as intermixed cation layers for z = 5, within the SLs. The G Ge(x+y)Sb(2–y)Tez units are separated from the Sb2Te3 building blocks by van der Waals gaps. In particular, the interlayer bonding is promoted by the formation of outermost cation layers consisting of intermixed GeSb within the building blocks adjacent to the van der Waals gaps. The Ge(x+y)Sb(2–y)Tez units with z > 5 retain metastable crystal structures with two-dimensional bonding within the SLs. The present study shed new light on the possible configurations of the building units that can be formed during the synthesis of GeTe-Sb2Te3-based iPCM materials. In addition, a possible switching mechanism active in iPCM materials is discussed.

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References

  1. Feinleib, J.; Deneufville, J.; Moss, S. C.; Ovshinsky, S. R. Rapid reversible light-induced crystallization of amorphous semiconductors. Appl. Phys. Lett. 1971, 18, 254–257.

    Article  Google Scholar 

  2. Wuttig, M.; Yamada, N. Phase-change materials for rewriteable data storage. Nat. Mater. 2007, 6, 824–832.

    Article  Google Scholar 

  3. Simpson, R. E.; Fons, P.; Kolobov, A. V.; Fukaya, T.; Krbal, M.; Yagi, T.; Tominaga, J. Interfacial phase-change memory. Nat. Nanotechnol. 2011, 6, 501–505.

    Article  Google Scholar 

  4. Momand, J.; Wang, R. N.; Boschker, J. E.; Verheijen, M. A.; Calarco, R.; Kooi, B. J. Interface formation of two- and three-dimensionally bonded materials in the case of GeTe-Sb2Te3 superlattices. Nanoscale 2015, 7, 19136–19143.

    Article  Google Scholar 

  5. Wang, R. N.; Bragaglia, V.; Boschker, J. E.; Calarco, R. Intermixing during epitaxial growth of van der Waals bonded nominal GeTe/Sb2Te3 superlattices. Cryst. Growth Des. 2016, 16, 3596–3601.

    Article  Google Scholar 

  6. Casarin, B.; Caretta, A.; Momand, J.; Kooi, B. J.; Verheijen, M. A.; Bragaglia, V.; Calarco, R.; Chukalina, M.; Yu, X. M.; Robertson, J. et al. Revisiting the local structure in Ge-Sb-Te based chalcogenide superlattices. Sci. Rep. 2016, 6, 22353.

    Article  Google Scholar 

  7. Momand, J.; Lange, F. R. L.; Wang, R. N.; Boschker, J. E.; Verheijen, M. A.; Calarco, R.; Wuttig, M.; Kooi, B. J. Atomic stacking and van-der-Waals bonding in GeTe-Sb2Te3 superlattices. J. Mater. Res. 2016, 31, 3115–3124.

    Article  Google Scholar 

  8. Lotnyk, A.; Ross, U.; Bernütz, S.; Thelander, E.; Rauschenbach, B. Local atomic arrangements and lattice distortions in layered Ge-Sb-Te crystal structures. Sci. Rep. 2016, 6, 26724.

    Article  Google Scholar 

  9. Tominaga, J.; Kolobov, A. V.; Fons, P.; Nakano, T.; Murakami, S. Ferroelectric order control of the dirac-semimetal phase in GeTe-Sb2Te3 superlattices. Adv. Mater. Interfaces 2014, 1, 1300027.

    Article  Google Scholar 

  10. Tominaga, J.; Kolobov, A. V.; Fons, P. J.; Wang, X. M.; Saito, Y.; Nakano, T.; Hase, M.; Murakami, S.; Herfort, J.; Takagaki, Y. Giant multiferroic effects in topological GeTe-Sb2Te3 superlattices. Sci. Technol. Adv. Mater. 2015, 16, 014402.

    Article  Google Scholar 

  11. Ohyanagi, T.; Kitamura, M.; Araidai, M.; Kato, S.; Takaura, N.; Shiraishi, K. GeTe sequences in superlattice phase change memories and their electrical characteristics. Appl. Phys. Lett. 2014, 104, 252106.

    Article  Google Scholar 

  12. Yu, X. M.; Robertson, J. Modeling of switching mechanism in GeSbTe chalcogenide superlattices. Sci. Rep. 2015, 5, 12612.

    Article  Google Scholar 

  13. Yu, X. M.; Robertson, J. Atomic layering, intermixing and switching mechanism in Ge-Sb-Te based chalcogenide superlattices. Sci. Rep. 2016, 6, 37325.

    Article  Google Scholar 

  14. Kalikka, J.; Zhou, X. L.; Behera, J.; Nannicini, G.; Simpson, R. E. Evolutionary design of interfacial phase change van der Waals heterostructures. Nanoscale 2016, 8, 18212–18220.

    Article  Google Scholar 

  15. Lotnyk, A.; Poppitz, D.; Ross, U.; Gerlach, J. W.; Frost, F.; Bernuütz, S.; Thelander, E.; Rauschenbach, B. Focused highand low-energy ion milling for TEM specimen preparation. Microelectroni. Reliab. 2015, 55, 2119–2125.

    Article  Google Scholar 

  16. Barthel, J. Probe-STEM simulation software[Online]. http:// www.er-c.org/barthel/drprobe.

  17. Schneider, M. N.; Oeckler, O. Unusual solid solutions in the system Ge-Sb-Te: The crystal structure of 33RGe4-xSb2-yTe7(x, y ˜ 0.1) is Isostructural to that of Ge3Sb2Te6. Z. Anorg. Allg. Chem. 2008, 634, 2557–2561.

    Article  Google Scholar 

  18. Urban, P.; Schneider, M. N.; Erra, L.; Welzmiller, S.; Fahrnbauer, F.; Oeckler, O. Temperature dependent resonant X-ray diffraction of single-crystalline Ge2Sb2Te5. CrystEngComm 2013, 15, 4823–4829.

    Article  Google Scholar 

  19. Kokh, K. A.; Atuchin, V. V.; Gavrilova, T. A.; Kuratieva, N. V.; Pervukhina, N. V.; Surovtsev, N. V. Microstructural and vibrational properties of PVT grown Sb2Te3 crystals. Solid State Commun. 2014, 177, 16–19.

    Article  Google Scholar 

  20. Bauer Pereira, P.; Sergueev, I.; Gorsse, S.; Dadda, J.; Müller, E.; Hermann, R. P. Lattice dynamics and structure of GeTe, SnTe and PbTe. Phys. Status Solidi B 2013, 250, 1300–1307.

    Article  Google Scholar 

  21. Ross, U.; Lotnyk, A.; Thelander, E.; Rauschenbach, B. Direct imaging of crystal structure and defects in metastable Ge2Sb2Te5 by quantitative aberration-corrected scanning transmission electron microscopy. Appl. Phys. Lett. 2014, 104, 121904.

    Article  Google Scholar 

  22. Lotnyk, A.; Bernütz, S.; Sun, X. X.; Ross, U.; Ehrhardt, M.; Rauschenbach, B. Real-space imaging of atomic arrangement and vacancy layers ordering in laser crystallised Ge2Sb2Te5 phase change thin films. Acta Mater. 2016, 105, 1–8.

    Article  Google Scholar 

  23. Mio, A. M.; Privitera, M. S.; Bragaglia, V.; Arciprete, F.; Bongiorno, C.; Calarco, R.; Rimini, E. Chemical and structural arrangement of the trigonal phase in GeSbTe thin films. Nanotechnology 2017, 28, 065706.

    Article  Google Scholar 

  24. Hilmi, I.; Lotnyk, A.; Gerlach, J. W.; Schumacher, P.; Rauschenbach, B. Epitaxial formation of cubic and trigonal Ge-Sb-Te thin films with heterogeneous vacancy structures. Mater. Des. 2017, 115, 138–146.

    Article  Google Scholar 

  25. Hartel, P.; Rose, H.; Dinges, C. Conditions and reasons for incoherent imaging in STEM. Ultramicroscopy 1996, 63, 93–114.

    Article  Google Scholar 

  26. Rafferty, B.; Nellist, D.; Pennycook, J. On the origin of transverse incoherence in Z-contrast STEM. J. Electron Microsc. 2001, 50, 227–233.

    Google Scholar 

  27. Wang, Z. W.; Li, Z. Y.; Park, S. J.; Abdela, A.; Tang, D.; Palmer, R. E. Quantitative Z-contrast imaging in the scanning transmission electron microscope with size-selected clusters. Phys. Rev. B 2011, 84, 073408.

    Article  Google Scholar 

  28. Kim, S.; Jung, Y.; Kim, J. J.; Lee, S.; Lee, H. Z-contrast dependence of quantitative scanning transmission electron microscopy image of Si1-xGex binary crystals. J. Alloys Compd. 2015, 618, 545–550.

  29. Ross, U.; Lotnyk, A.; Thelander, E.; Rauschenbach, B. Microstructure evolution in pulsed laser deposited epitaxial Ge-Sb-Te chalcogenide thin films. J. Alloys Compd. 2016, 676, 582–590.

    Article  Google Scholar 

  30. Hurych, Z.; Benbow R. L. Photoemission studies of interface properties of thin Bi overlayers on two-dimensional crystals of BixSb2-xTe3 semiconductors using synchrotron radiation. Phys. Rev. B 1977, 16, 3707–3712.

    Article  Google Scholar 

  31. Wagner, V.; Doling, G.; Powell, B.M.; Landweher, G. Lattice vibrations of Bi2Te3. Phys. Status Solidi B 1978, 85, 311–317.

    Article  Google Scholar 

  32. Sa, B. S.; Miao, N. H.; Zhou, J.; Sun, Z. M.; Ahuja, R. Ab initio study of the structure and chemical bonding of stable Ge3Sb2Te6. Phys. Chem. Chem. Phy. 2010, 12, 1585–1588.

    Article  Google Scholar 

  33. Matsunaga, T.; Kojima, R.; Yamada, N.; Kifune, K.; Kubota, Y.; Takata, M. Structural investigation of Ge3Sb2Te6, an intermetallic compound in the GeTe-Sb2Te3 homologous series. Appl. Phys. Lett. 2007, 90, 161919.

    Article  Google Scholar 

  34. Matsunaga, T.; Yamada, N.; Kubota, Y. Structures of stable and metastable Ge2Sb2Te5, an intermetallic compound in GeTe-Sb2Te3 pseudobinary systems. Acta Cryst. B 2004, 60, 685–691.

    Article  Google Scholar 

  35. Da Silva, J. L. F.; Walsh, A.; Lee, H. Insights into the structure of the stable and metastable (GeTe)m(Sb2Te3)m compounds. Phys. Rev. B 2008, 78, 224111.

    Article  Google Scholar 

  36. Gorbenko, O. Y.; Samoilenkov, S. V.; Graboy, I. E.; Kaul, A. R. Epitaxial stabilization of oxides in thin films. Chem. Mat. 2002, 14, 4026–4043.

    Article  Google Scholar 

  37. Lotnyk, A.; Senz, S.; Hesse, D. Orientation relationships of SrTiO3 and MgTiO3 thin films grown by vapor-solid reactions on (100) and (110) TiO2(rutile) single crystals. J. Phys. Chem. C 2007, 111, 6372–6379.

    Article  Google Scholar 

  38. Lee, S.; Ivanov, I. N.; Keum, J. K.; Lee, H. N. Epitaxial stabilization and phase instability of VO2 polymorphs. Sci. Rep. 2016, 6, 19621.

    Article  Google Scholar 

  39. Gaspard, J. P.; Ceolin, R. Hume-rothery rule in V-VI compounds. Solid State Commun. 1992, 84, 839–842.

    Article  Google Scholar 

  40. Gaspard, J. P. Structure of covalently bonded materials: From the peierls distortion to phase-change materials. C. R. Phys. 2016, 17, 389–405.

    Article  Google Scholar 

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Acknowledgements

We would like to thank Mrs. A. Mill for her assistance in the TEM specimen preparation by FIB. The financial support of the European Union and the Free State of Saxony (LenA project; project No. 100074065) is greatly acknowledged.

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Authors and Affiliations

  1. Leibniz Institute of Surface Modification (IOM), Permoserstr. 15, Leipzig, D-04318, Germany

    Andriy Lotnyk, Isom Hilmi, Ulrich Ross & Bernd Rauschenbach

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  1. Andriy Lotnyk
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  3. Ulrich Ross
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  4. Bernd Rauschenbach
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Correspondence to Andriy Lotnyk.

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Lotnyk, A., Hilmi, I., Ross, U. et al. Van der Waals interfacial bonding and intermixing in GeTe-Sb2Te3-based superlattices. Nano Res. 11, 1676–1686 (2018). https://doi.org/10.1007/s12274-017-1785-y

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  • DOI: https://doi.org/10.1007/s12274-017-1785-y

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