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Directed Electrochemical Directed Electrochemical Nanowire Assembly Nanowire Assembly

SRINIVASA REDDYSRINIVASA REDDY

Department of PhysicsDepartment of PhysicsOklahoma State UniversityOklahoma State University

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IntroductionIntroduction

• A critical issue in nanoscience is the conduction through very thin metallic wires.

• As the wire diameter decreases the mean free path for conduction electrons decreases, leading to the inelastic collision of the electrons with the boundary surfaces of the metal.

• Experimental verification of this issue is ambiguous and requires the fabrication of diameter-tunable, single-crystal, metallic nanowires with low contact resistance interfacing in the external circuitry.

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Directed Electrochemical Nanowire Assembly (DENA)Directed Electrochemical Nanowire Assembly (DENA)

• Palladium wires from

palladium acetate solution.*

• Developed DENA technique**:

• Single-step growth and interfacing of (near) single-crystalline metallic nanowires from simple salt solutions.

*C. Cheng, R.K.G., Q. Gu, and D. T. Haynie, Nano Letters, 5, 175, 2005

**I. Talukdar, B. Ozturk, T.D. Mishima, B.N. Flanders, Appl. Phys. Lett., 88, 221907 (2006)

**B. Ozturk, D.R. Grischkowsky, T.D. Mishima and B.N. Flanders, Nanotechnology, 18, 175707 (2007)

20 m

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Structural variation of indium wiresStructural variation of indium wires

• Control of the growth voltage and solution concentration gives rise to structural variation: (b) amorphous, (c) dendritic, (d) needle.

I. Talukdar, B. Ozturk, T.D. Mishima, B.N. Flanders, Appl. Phys. Lett., 88, 221907. (2006)

20 m 20 m

20 m

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1 m 1 m 1 m

0.5 MHz 1.0 MHz 3.5 MHz

Frequency dependent diameterFrequency dependent diameter

• SEM micrographs of indium wires grown with increasing growth frequency.

I. Talukdar, B. Ozturk, B. N. Flanders, In preparation. (2007)

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• As the growth frequency increases, the wire diameter decreases.

Frequency dependent diameterFrequency dependent diameter

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• Wire growth velocity increases with increasing frequency.

• Velocity and diameter are anti-correlated: signature of dendriticgrowth.*

Frequency dependent velocityFrequency dependent velocity

* G. P. Ivantsov, Dokl. Akad. Nauk. SSSR 58, 567 (1947) J. S. Langer and H. Muller-Krumbhaar, Acta. Metall. 26, 1961 (1978)

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ConclusionsConclusions

• DENA technique allows the single-step growth and interfacing of crystalline, metallic submicron wires from simply prepared solutions.

• Wire diameter is tunable down to ~ 100 nm with the control of the growth frequency.

• These capabilities will facilitate future studies of diameter-dependent transport measurements with the DENA technique.

• We applied DENA technique to the growth of In, Ni, Au, Co, Cu, Ag, Zn and Pb wires.

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AcknowledgementsAcknowledgements

• Dr. Bret N. Flanders

• Dr. Birol Ozturk

• Prem Thapa

FUNDING

NER-304413 EPS-132354 ECS-0601362

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