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Atomic-scale imaging of nanoengineered oxygen vacancy profiles in SrTiO3

Nature volume 430, pages 657–661 (2004)Cite this article

Abstract

At the heart of modern oxide chemistry lies the recognition that beneficial (as well as deleterious) materials properties can be obtained by deliberate deviations of oxygen atom occupancy from the ideal stoichiometry1,2. Conversely, the capability to control and confine oxygen vacancies will be important to realize the full potential of perovskite ferroelectric materials, varistors and field-effect devices3,4. In transition metal oxides, oxygen vacancies are generally electron donors, and in strontium titanate (SrTiO3) thin films, oxygen vacancies (unlike impurity dopants) are particularly important because they tend to retain high carrier mobilities, even at high carrier densities5. Here we report the successful fabrication, using a pulsed laser deposition technique, of SrTiO3 superlattice films with oxygen doping profiles that exhibit subnanometre abruptness. We profile the vacancy concentrations on an atomic scale using annular-dark-field electron microscopy and core-level spectroscopy, and demonstrate absolute detection sensitivities of one to four oxygen vacancies. Our findings open a pathway to the microscopic study of individual vacancies and their clustering, not only in oxides, but in crystalline materials more generally.

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Figure 1: Electron energy-loss spectra (EELS) for oxygen-deficient SrTiO3-δ, for δ ≈ 0, 0.13 and 0.25.
Figure 2: 25 unit cells of oxygen-deficient SrTiO3-δ (δ ≈ 0.13) are grown on bulk SrTiO3 (left of white arrow) and capped with a two-layer-thick LaTiO3 marker layer (right) and more SrTiO3-δ.
Figure 3: Quantitative line profiles through the oxygen-deficient layer.
Figure 4: A LAADF image of an oxygen-modulated superlattice grown on SrTiO3.

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References

  1. Majewski, P. BiSrCaCuO high-Tc superconductors. Adv. Mater. 6, 460–469 (1994)

    Article  CAS  Google Scholar 

  2. Shimakawa, Y., Kubo, Y., Manako, T. & Igarashi, H. Variation in Tc and carrier concentration in Tl-based superconductors. Phys. Rev. B 40, 11400–11402 (1989)

    Article  ADS  CAS  Google Scholar 

  3. Greuter, F. & Blatter, G. Electrical properties of grain boundaries in polycrystalline compound semiconductors. Semicond. Sci. Technol. 5, 111–137 (1990)

    Article  ADS  CAS  Google Scholar 

  4. Ahn, C. H., Triscone, J.-M. & Mannhart, J. Electric field effect in correlated oxide systems. Nature 424, 1015–1018 (2004)

    Article  ADS  Google Scholar 

  5. Tufte, O. N. & Chapman, P. W. Electron mobility in semiconducting strontium titanate. Phys. Rev. 155, 796–802 (1967)

    Article  ADS  CAS  Google Scholar 

  6. Sze, S. M. Semiconductor Devices: Physics and Technology (John Wiley, New York, 1986)

    Google Scholar 

  7. Pellegrino, L., Pallecchi, I., Marré, D., Bellingeri, E. & Siri, A. S. Fabrication of submicron-scale SrTiO3-δ devices by an atomic force microscope. Appl. Phys. Lett. 81, 3849–3851 (2002)

    Article  ADS  CAS  Google Scholar 

  8. Burgy, J., Mayr, M., Martin-Mayor, V., Moreo, A. & Dagotto, E. Colossal effects in transition metal oxides caused by intrinsic inhomogeneities. Phys. Rev. Lett. 87, 277202 (2001)

    Article  ADS  CAS  Google Scholar 

  9. Jia, C. L., Lentzen, M. & Urban, K. Atomic-resolution imaging of oxygen in perovskite ceramics. Science 299, 870–873 (2003)

    Article  ADS  CAS  Google Scholar 

  10. Voyles, P. M., Muller, D. A., Grazul, J. L., Citrin, P. H. & Gossmann, H.-J. L. Atomic-scale imaging of individual dopant atoms and clusters in highly n-type bulk Si. Nature 416, 826–829 (2002)

    Article  ADS  CAS  Google Scholar 

  11. Kaiser, U., Muller, D. A., Grazul, J., Chuvulin, A. & Kawasaki, M. Direct observation of defect-mediated cluster nucleation. Nature Mater. 1, 102–105 (2002)

    Article  ADS  CAS  Google Scholar 

  12. Muller, D. A. & Grazul, J. Optimizing the environment for sub-0.2 nm scanning transmission electron microscopy. J. Elec. Microsc. 50, 219–226 (2001)

    CAS  Google Scholar 

  13. Batson, P. E. Simultaneous STEM imaging and electron energy-loss spectroscopy with atomic column sensitivity. Nature 366, 727–728 (1993)

    Article  ADS  CAS  Google Scholar 

  14. Browning, N. D., Chisholm, M. M. & Pennycook, S. J. Atomic-resolution chemical analysis using a scanning transmission electron microscope. Nature 366, 143–146 (1993)

    Article  ADS  CAS  Google Scholar 

  15. Muller, D. A. et al. The electronic structure at the atomic scale of ultra-thin gate oxides. Nature 399, 758–761 (1999)

    Article  ADS  CAS  Google Scholar 

  16. Egerton, R. F. Electron Energy Loss Spectroscopy in the Electron Microscope (Plenum, New York, 1996)

    Book  Google Scholar 

  17. Zhang, Z., Sigle, W. & Rühle, M. Atomic and electronic characterization of the a[100] dislocation core in SrTiO3 . Phys. Rev. B 66, 094108 (2002)

    Article  ADS  Google Scholar 

  18. Browning, N. D., Moltaji, H. O. & Buban, J. P. Investigation of three-dimensional grain-boundary structures in oxides through multiple-scattering analysis of spatially resolved electron-energy-loss spectra. Phys. Rev. B 58, 8289–8300 (1998)

    Article  ADS  CAS  Google Scholar 

  19. Yamada, H. & Miller, G. R. Point defects in reduced strontium titanate. J. Solid State Chem. 6, 169–177 (1973)

    Article  ADS  CAS  Google Scholar 

  20. Gong, W. et al. Oxygen-deficient SrTiO3-x, x = 0.28, 0.17, 0.08. Crystal growth, crystal structures, magnetic, and transport properties. J. Solid State Chem. 90, 320–330 (1991)

    Article  ADS  CAS  Google Scholar 

  21. Abbate, M. et al. Soft-x-ray-absorption studies of the location of extra charges induced by substitution in controlled-valence materials. Phys. Rev. B 44, 5419–5422 (1991)

    Article  ADS  CAS  Google Scholar 

  22. Ohtomo, A., Muller, D. A., Grazul, J. L. & Hwang, H. Y. Epitaxial growth and electronic structure of LaTiOx films. Appl. Phys. Lett. 80, 3922–3925 (2002)

    Article  ADS  CAS  Google Scholar 

  23. Ohtomo, A., Muller, D. A., Grazul, J. L. & Hwang, H. Y. Artificial charge-modulation in atomic-scale perovskite titanate superlattices. Nature 419, 378–380 (2002)

    Article  ADS  CAS  Google Scholar 

  24. Howie, A. Image contrast and localized signal selection techniques. J. Microsc. 17, 11–23 (1979)

    Article  Google Scholar 

  25. Kirkland, E. J., Loane, R. F. & Silcox, J. Simulation of annular dark field STEM images using a modified multislice method. Ultramicroscopy 23, 77–96 (1987)

    Article  Google Scholar 

  26. Hillyard, S. E. & Silcox, J. Detector geometry, thermal diffuse scattering and strain effects in ADF STEM imaging. Ultramicroscopy 58, 6–17 (1995)

    Article  CAS  Google Scholar 

  27. Perovic, D. D., Rossow, C. J. & Howie, A. Imaging elastic strains in high-angle annular dark-field scanning-transmission electron microscopy. Ultramicroscopy 52, 353–359 (1993)

    Article  CAS  Google Scholar 

  28. Voyles, P. M., Muller, D. A. & Kirkland, E. J. Depth-dependent imaging of individual dopant atoms in silicon. Microsc. Microanal. 10, 291–300 (2004)

    Article  ADS  CAS  Google Scholar 

  29. Szot, K., Speier, W., Carius, R., Zastrow, U. & Beyer, W. Localized metallic conductivity and self-healing during thermal reduction of SrTiO3 . Phys. Rev. Lett. 88, 075508 (2002)

    Article  ADS  CAS  Google Scholar 

  30. Szot, K. & Speier, W. Surfaces of reduced and oxidized SrTiO3 from atomic force microscopy. Phys. Rev. B 60, 5909–5926 (1999)

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

We acknowledge partial support from NEDO's International Joint Research Program. N.N. acknowledges partial support from QPEC, Graduate School of Engineering, University of Tokyo. D.A.M. and J.L.G. received partial support from the Cornell Center for Materials Research, a NSF materials research science and engineering centre.

Author information

Authors and Affiliations

  1. Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey, 07974, USA

    David A. Muller, Naoyuki Nakagawa, Akira Ohtomo, John L. Grazul & Harold Y. Hwang

  2. School of Applied and Engineering Physics, Cornell University, Ithaca, New York, 14583, USA

    David A. Muller & John L. Grazul

  3. Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan

    Naoyuki Nakagawa & Harold Y. Hwang

  4. Institute of Materials Research, Tohoku University, 980-8577, Sendai, Japan

    Akira Ohtomo

  5. Japan Science and Technology Agency, 332-0012, Kawaguchi, Japan

    Harold Y. Hwang

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  1. David A. Muller
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Correspondence to David A. Muller.

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Supplementary information

Supplementary Figures

Supplementary Fig 1. Oxygen-deficient SrTiO3-δ, (δ ≈ 0.25) are grown on bulk SrTiO3 ( 700 ºC, PO2=2x 10-8 torr). Supplementary Fig 2. A LAADF image of an oxygen-modulated superlattice grown on SrTiO3. (PDF 1143 kb)

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Muller, D., Nakagawa, N., Ohtomo, A. et al. Atomic-scale imaging of nanoengineered oxygen vacancy profiles in SrTiO3. Nature 430, 657–661 (2004). https://doi.org/10.1038/nature02756

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