Researchers:
Gerd Woerhle
Evan Foster
Mike Jespersen
Greg Kearns
Scott Sweeney
Carley Corrado
Andy Ritenour

Funding By:

Keywords:Electronic materials chemistry, nanoparticle synthesis and functionalization, nanoparticle arrays, biopolymer templating, biomolecular lithography, nanoelectronics, electron transfer.

Goal #1: Investigate new methods (and mechanisms) for synthesis of well-defined, functionalized nanoparticles and develop chemical methods for arrangement of nanoparticle arrays.

Utilizing synthetic methods developed in our lab, we can prepare gold nanoparticles with well-defined core sizes, solubilities, interparticle spacings and reactivities. We can further optimize or “tune” the properties of the nanoparticles by adjusting the identity and ratio of reactive bridging to inert capping ligands. Our method utilizes ligand exchange reactions where the ligand shell of a triphenylphosphine stabilized particle is replaced with a thiol or amine ligand shell. This procedure is versatile, rapid and reproducible.

We have discovered methods for forming well-ordered nanoparticle monolayers and multilayers on insulating surfaces for use in nanoelectronic devices. The Hutchison lab has also developed methods for forming one- and two-dimensional nanoparticle structures using DNA as a template.

Goal #2: Study the electron transport characteristics of well-defined nanoparticle arrays. Use this knowledge to design and fabricate nanoelectronic devices.

Chemical fabrication of devices that operate on the basis of Coulomb blockade (e.g. a single electron transistor) promises to provide computer chips with 10,000 times more electronic devices than possible with state-of-the-art lithography. In order to build a single electron transistor that operates at room temperature, particles smaller than two nanometers in diameter must be used. Additionally, the nanoparticles need to be assembled between electrode contacts. Research in this area is aimed at developing chemical and lithographic methods to bridge the gap between the nanoscale and microscale so that our assemblies can be utilized as nanoelectronic devices and test structures. Techniques under development include patterning of two-dimensional nanoparticle arrays by electron-beam and optical lithography. We also aim to span electrode gaps with one-dimensional DNA/nanoparticle arrays by stretching the assemblies using solvent flow or specific chemical interactions. Using the thin films described in the section above, we (in collaboration with Martin Wybourne's lab at Dartmouth) have explored the electrical properties of nanoparticle assemblies. These samples provide the first observation of Coulomb blockade at room temperature in a two- or three-dimensional nanoparticle array and demonstrate that our nanoparticle building blocks are well suited for the construction of Coulomb blockade devices. We have also observed room temperature Coulomb blockade in linear nanoparticle/polymer assemblies.

Recent publications associated with this project:

Clark, L.; Wybourne, M. N.; Yan, M.; Cai, S. X.; Brown, L. O.; Hutchison, J.; Keana, J. F. W. "Fabrication and Near-Room Temperature Transport of Patterned Gold Cluster Structures," J. Vac. Sci. Tech. B, 1997, 15, 2925-2929.

Brown, L. O.; Hutchison, J. E. "Convenient Preparation of Stable, Narrow-Dispersity, Gold Nanocrystals by Ligand Exchange Reactions," J. Am. Chem. Soc. 1997, 119, 12384-12385.

Clarke, L.; Wybourne, M. N.; Brown, L. O.; Hutchison, J. E.; Yan, M.; Cai, S. X.; Keana, J. F. W. "Room Temperature Coulomb-Blockade Dominated Transport in Gold-Nanocluster Structures," Semicond. Sci. Technol. 1998, 13, A111-A114.

Brown, L. O.; Hutchison, J. E. "Controlled Growth of Gold Nanoparticles During Ligand Exchange," J. Am. Chem. Soc. 1999, 121, 882-883.

Wybourne, M.N.; Hutchison, J.E.; Clarke, L.; Brown L.O.; Mooster, J.L. "Fabrication and Electrical Transport Characteristics of Low-Dimensional Nanoparticle Arrays Organized by Biomolecular Scaffolds," Microelcetron Eng. 1999, 47, 55-57.

Weare, W.W; Reed, S.M.; Warner, M.G.; Hutchison, J.E. “Improved Synthesis of Small (dCORE =1.5 nm) Phosphine-stabilized Nanoparticles” J. Am. Chem. Soc., 2000, 122, 12890-12891.

Berven, C. A.; Wybourne, M. N.; Clarke, L.; Hutchison, J. E; Brown, L. O.; Mooster J. L; Schmidt, M. E.; “The Use of Biopolymer Templates to Fabricate Low-Dimensional Gold Particle Structures” Superlattices and Microstructures, 2000, 27, 489-493.

Warner, M. G.; Reed, S. M.; Hutchison, J. E. “Small, Water-soluble, Ligand-stabilized Gold Nanoparticles Synthesized by Interfacial Ligand Exchange Reactions,” Chem. Mater. 2000,12, 3316-3320. abstract

Berven, C. A.; Clarke, L.; Mooster J. L., Wybourne, M. N.; Hutchison, J. E.; “Defect-Tolerant Single Electron Charging at Room Temperature in Metal Nanoparticle Decorated Biopolymers” Adv. Mater. 2001, 13, 109-113.

Woehrle, G. H.; Warner, M. G.; Hutchison, J. E. “Ligand Exchange Reactions Yield Subnanometer, Thiol-Stabilized Gold Particles with Defined Optical Transitions,” J. Phys. Chem. B 2002, 106, 9979-9981.

Warner, M. G.; Hutchison, J. E. “Linear assemblies of nanoparticles electrostatically organized on DNA scaffolds,” Nature Materials 2003, 2, 272-277.

Warner, M. G.; Hutchison, J. E. “Synthesis, Functionalization and Surface Treatment of Nanoparticles,” 2003, 67-89.