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Tunable electronic interfaces between bulk semiconductors and ligand-stabilized nanoparticle assemblies

Nature Materials volume 6, pages 592–596 (2007)Cite this article

Abstract

Interfaces between nanoscale and bulk electroactive materials are important for the design of electronic devices using solution-processed nanoparticles. We report that thin films of hexanethiolate-capped gold nanoparticles with a core diameter of 2.1±0.4 nm deposited onto n-InP wafers form Schottky contacts whose barrier height can be actively tuned from 0.27±0.03 to 1.11±0.09 eV by electrochemically adjusting the nanoparticle Fermi level. This result is remarkable because interfacial barriers at conventional metal–semiconductor contacts are largely insensitive to the initial Fermi level of the metal. Furthermore, it highlights two general features of solution-processed nanoparticle assemblies in comparison with traditional bulk electronic materials: (1) the ability of ions to permeate the nanoparticle assembly enables the electrochemical injection of charges and hence active control of the Fermi level, and (2) ligand passivation of nanoparticle surfaces prevents interfacial reactions with the semiconductor that could otherwise lead to strong Fermi-level pinning.

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Figure 1: Energy band diagrams for the formation of an ideal n-type semiconductor–metal interface.
Figure 2: Nanoparticle electrochemistry.
Figure 3: Cross-section schematic diagram of the AuNP–InP device.
Figure 4: Current–voltage analysis.
Figure 5: Mott–Schottky analysis.

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Acknowledgements

We thank E. McFarland, H. Nienhaus, N. Zheng and A. Ivanovskaya for insightful discussion. This work was supported by the NSF under awards DMR-02-33728 and ECCS-0609485, the Air Force Research Laboratory under agreement FA8650-05-1-5041 and the US Army Research Office via the Institute for Collaborative Biotechnologies through grant DAAD19-03D-0004, and made use of the MRL central facilities supported by the MRSEC Program of the NSF under award DMR-05-20415. S.W.B. thanks the NSF for a Graduate Research Fellowship.

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Authors and Affiliations

  1. Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA

    Shannon W. Boettcher, Martin Schierhorn & Galen D. Stucky

  2. Materials Department, University of California, Santa Barbara, California 93106, USA

    Nicholas C. Strandwitz & Galen D. Stucky

  3. Department of Chemistry, University of Aarhus, DK-8000 Aarhus C, Denmark

    Nina Lock

  4. Department of Chemistry, The Materials Science Institute, Oregon Nanoscience and Microtechnologies Institute, University of Oregon, Eugene, Oregon 97403, USA

    Mark C. Lonergan

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Correspondence to Galen D. Stucky.

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Boettcher, S., Strandwitz, N., Schierhorn, M. et al. Tunable electronic interfaces between bulk semiconductors and ligand-stabilized nanoparticle assemblies. Nature Mater 6, 592–596 (2007). https://doi.org/10.1038/nmat1943

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