Aligned Growth of ZnO Nanorods

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Aligned Growth of ZnO Nanorods

• Justin Hwa
• Advisors Dr. ZL Wang, Jinhui Song
• August 4th, 2005

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Outline

• Introduction
• Nanotechnology
• Zinc Oxide (properties, structures, potential
  applications)
• ZnO Synthesis
• Thermal Evaporation
• Tube Furnace
• Growth Mechanisms
• Data Results
• Summary

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Introduction
4
Nanotechnology

• The construction and use of functional
  structures designed from the atomic or the
  molecular scale with at least one characteristic
  dimension measured in nanometers (1100 nm).

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Zinc Oxide

• Basic Properties
• band gap 3.4eV, direct
• exciton binding energy 60 meV
• piezoelectricity 12.4 pm/V
• Nanostructures
• nanobelts, nanowires, nanorods, nanosprings,
  nanorings, nanosaws, nanocombs, etc.
• Potential Applications
• cantilevers, field-effect transistors, gas
  sensors, photonic crystal, etc.

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ZnO Synthesis
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Thermal Evaporation

• One of the simplest and most popular synthesis
  methods.
• Very successful and versatile in fabricating
  nanobelts and nanowires with various
  characteristics.
• Process sublimation of source material ?
  deposition of vapor at certain temperature
  region.
• Processes
• w/ carbon catalyst
• ZnO(s) C(s) ? Zn(v) CO(v)
• w/o carbon catalyst
• 1. 2ZnO(s) ? 2Zn(v) O2(v)
• 2. ZnO(s) ? ZnO(v)

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Tube Furnace
Tube Furnace
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Growth Mechanisms

• Vapor-Solid
• Vapor-Liquid-Solid (VLS)

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Data Results

• Sample Data
• ZnO B46 7-22-2005
• Source Materials ZnO - 0.6g C - 0.6g
• Substrate AlGaNMg catalyst, sputter 30 Au
• 25cm from the end
• Low temperature furnace
• Small valve 0.1 mbar
• Big valve 4.0 x 10-2 mbar
• Heat rate 50C/min
• Keep at 950C for 30 minutes
• Gas Ar 49.0 sccm
• O2 1.0 sccm
• Keep pressure at 30 mbar

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Data Results
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Summary
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Acknowledgements

• Dr. Leyla Conrad
• Dr. ZL Wang
• Jinhui Song
• Changshi Lao
• Dr. Wangs nanoscience research group
• MARTA the Ga Tech Trolley

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Questions?