Fabrication of Pure

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AMRI, Summer Research 2006, University of New
Orleans
Fabrication of Pure Doped TiO2 SnO Nanowires
for Spintronics
Omagbe D. Fregene, Jiajun Chen, Dr Weilie Zhou
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AMRI, Summer Research 2006, University of New
Orleans

• Abstract

The following experiments were centered on
fabricating TiO2 and SnO nanostructures. The
great potentials of creating TiO2 nanostructures,
particularly nanowires, was all the motivation I
needed. In time though, the high level of
difficulty that follows this material would prove
to be a very stiff challenge. The method employed
in the fabrication of nanostructures in the
following experiments is the Physical Vapor
deposition Method. In the VDM the source
material vaporizes and is carried by the flow gas
to the substrate where it deposits and grows via
the bottom up approach. After numerous attempts
to fabricate TiO2 Nanowires, TiO2 Nanoparticles
were obtained. But after only a few attempts, SnO
nanowires were successfully fabricated. The size
of the TiO2 and SnO nanoparticles range from 5µm
20nm and 1-20µm respectively.
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AMRI, Summer Research 2006, University of New
Orleans

• Introduction

What are Nanowires?
Nanowires are one-dimensional wires with
dimensions in the order of 10-9m. Various types
of Nanowires that exist are Metallic,
Semiconducting and Insulating Nanowires. Examples
are Ni, Pt (metallic), Au, Si, GaN (semi
conducting), and SiO2 and TiO2 (insulating)
nanowires.
Characteristics of Nanowires
Nanowires, specifically one Dimensional nanowires
represent the smallest structures in electronics
that can

• Efficiently transport electrical carriers

• Exhibit device function and thus be exploited
  as both the wiring and
• device elements in architecture for
  functional nanosystems.

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AMRI, Summer Research 2006, University of New
Orleans
How are nanowires produced?
The Top Down Approach

• Nanostructured material is fabricated by
  sculpting it from the macroscopic piece of
  unstructured material such as Silicon.
• Common techniques used for this purpose are
  lithography, etching, mechanical milling, and
  engineering using atomic force microscope.
• Example
• Suspended method

http//nanoatlas.ifs.hr/top-down_approach.html
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AMRI, Summer Research 2006, University of New
Orleans
The Bottom Up Approach

• Produced by sublimation of solid source material
  into gas and depositing onto a substrate.
• Examples
• The VLS (Vapor-liquid-Solid) Method
• Chemical vapor deposition (CVD)
• Laser ablation
• Thermal Evaporation

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AMRI, Summer Research 2006, University of New
Orleans
Experiment Setup
Thermal Evaporation Method

• Temperature Controlled Heat Furnace is used

• Vacuum pump is used in conjunction with Heat
  Furnace to create vacuum

• Pressure inside the chamber maintained at
• with a pressure valve

• Mass flow rate of carrier gas is kept constant

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AMRI University of New Orleans
Titanium Oxide (TiO2) Nanoparticles
Synthesis
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AMRI, Summer Research 2006, University of New
Orleans
Experiment Parameters
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AMRI, Summer Research 2006, University of New
Orleans
SEM Images Titanium Oxide (TiO2) Nanoparticles
Attempt 1
Attempt 2
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AMRI, Summer Research 2006, University of New
Orleans
SEM Images Titanium Oxide (TiO2) Nanoparticles
Attempt 3
Attempt 4
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AMRI, Summer Research 2006, University of New
Orleans
TEM Attempt 5
FESEM Image Attempt 5
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AMRI, Summer Research 2006, University of New
Orleans

• Experiment

Fabrication of Tin Oxide (SnO2) Nanoparticles
Synthesis
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AMRI, Summer Research 2006, University of New
Orleans
Experiment Parameters
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AMRI, Summer Research 2006, University of New
Orleans
SEM Images Tin Oxide (SnO2) Nanowires
Attempt 1
Attempt 1
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AMRI, Summer Research 2006, University of New
Orleans
SEM Images Tin Oxide (SnO2) Nanowires
Attempt 2-Sapphire
Attempt 2 -Silicon
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AMRI, Summer Research 2006, University of New
Orleans
TEM Image Tin Oxide (SnO2) Nanowires
Attempt 2 - Silicon
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AMRI, Summer Research 2006, University of New
Orleans
Conclusion

• The growth conditions for fabricating TiO2
  nanowires were very hard to
• determine.
• Pure and doped SnO2 nanowires and nanoparticles
  were successfully
• synthesized with different geometries and
  source materials.
• TiO2 nanoparticles were obtained by the thermal
  evaporation method.
• TiO2 and SnO2 nanoparticles nanowires show
  promising magnetic
• properties and could possibly be used to
  create nanoscale devices.

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AMRI, Summer Research 2006, University of New
Orleans
Acknowledgements
I would like to thank AMRI and NIRT for this
wonderful opportunity.