technical presentation ap4
TRANSCRIPT
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Field Emission Enhancement Field Emission Enhancement
from from
Patterned Gallium Nitride NanowiresPatterned Gallium Nitride Nanowires
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OverviewOverview
IntroductionIntroduction GaN nanowire growth
Experimental Procedures Results & Discussion
Field emission of GaN nanowires Experimental Procedures Results & Discussion
Conclusions
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ObjectiveObjective
Obtained ENHANCED Field Emission from patterned GaN nanowire films
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IntroductionIntroduction
Field Emitters ApplicationsUltrahigh Speed Devices
Electron Beam Lithography
Low Power & High Brightness Field
Emission Flat Panel Displays
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GaN for Field Emission Applications
IntroductionIntroduction
GaN
FE enhancement anticipated from GaN nanowires
1 I. Berishev et. al., APL, 73, 1808 (1998)2 B. L. Ward et. al., JAP, 84, 5238 (1998)
GaN Films1
GaN Pyramid Arrays2
Roughed GaN films2
Wide Bandgap (3.45 eV)Strong Chemical & Mechanical StabilitiesLow Electron Affinity (2.7~3.3 eV)
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IntroductionIntroduction Field Emission of GaN nanowire films
Issue - Screening effectSolution – Patterning the nanowires
3 H. M. Manohara et. al., JVST B, 23, 157 (2005)
Nanotubes in regular patterned arrays of bundles3
versus
dense mats nanotubes, thin films of nanotubes or arrayed individual nanotubes
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Experimental ProceduresExperimental Procedures
Schematic diagram of experimental setup
Gas InletTo Pump
248 nm KrF laser beam
Focus Lens
View Port
Substrate Heater
Rotating Target
Plasma Plume
n-Si substrate
n-Si substrateUnpatterned Patterned
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SEM Images
Results & DiscussionResults & Discussion
500 nm
100 nm
500 nm
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Results & DiscussionResults & Discussion
20 nm 2 nm
2.7245 Å(100)
(010)
(100)
(1-10)
TEM Images
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Experimental ProceduresExperimental Procedures
Schematic diagram of field emission measurement setup
Pump
Anode
Cathode
V/A 100 m
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Device characterization – Field Emission Study
With patterningWithout patterning
0.001 mA/cm2 0.96 mA/cm2
n-Si substraten-Si substrate
Results & Discussion
INCREASE 960 TIMES!!!
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Results & DiscussionResults & DiscussionField Emission of GaN nanowire films
With patterningWithout patterning
Substrate
FE collection Enhanced FE collection
Substrate
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ConclusionsConclusions Density patterned GaN nanowires synthesized by Density patterned GaN nanowires synthesized by
pulsed laser ablationpulsed laser ablation
THANK YOU
Morphology & Structure studied
Field Emission studiedTurn-on field = 8.4 V/m at 0.01 mA/cm2
Peak current density = 0.96 mA/cm2 at 10.8 V/m
Field Emission properties depend onGood crystalline qualityLow electron affinityDensity difference