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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

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

Introduction

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 (1~100 nm).

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.

ZnO Synthesis

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)

Tube Furnace

Substrate

Source Materials

Tube Furnace
Pump Cooling Water

Carrying Cooling Gas Water

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

Data & Results
Sample Data:
ZnO – B46 7-22-2005 Source Materials: ZnO - 0.6g C - 0.6g Substrate: AlGaN:Mg 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: 50°C/min Keep at 950°C for 30 minutes Gas: Ar – 49.0 sccm O2 – 1.0 sccm Keep pressure at 30 mbar

Data & Results

Summary

Acknowledgements
Dr. Leyla Conrad Dr. ZL Wang Jinhui Song Changshi Lao Dr. Wang’s nanoscience research group MARTA & the Ga Tech Trolley

Questions?


				
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posted:11/14/2009
language:English
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