1 directed electrochemical nanowire assembly srinivasa reddy department of physics oklahoma state...
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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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