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Atomic-scale imaging of nanoengineered oxygen vacancy profiles in SrTiO3

Nature volume 430, pages 657661 (05 August 2004) | Download Citation

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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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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

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, Sendai, 980-8577, Japan

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

    • Harold Y. Hwang

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Competing interests

The authors declare that they have no competing financial interests.

Corresponding author

Correspondence to David A. Muller.

Supplementary information

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  1. 1.

    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.

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https://doi.org/10.1038/nature02756

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