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Carbon NanoTubeApplications in FED- Device

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Hersh Jalil Hersh Jalil MSc. studentMSc. student

What is carbon nanotube (CNT)?

Application to field emission display

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• Carbon nanotubes are hexagonally shaped arrangements of carbon atoms that have been rolled into tubes.

• These tiny straw-like cylinders of pure carbon have useful electrical propeties. They have already been used to make tiny transistor and one-dimentional copper wire

Introduction: CARBON NANOTUBESCARBON NANOTUBES

• Carbon nanotubes, composed of interlocking carbon atoms, are 1000x thinner than an average human hair – but can be 200x stronger than steel.

~10 nm

CARBON NANOTUBESCARBON NANOTUBES

Introduction: common facts• Discovered in 1991 by Iijima

• Unique material properties

• Nearly one-dimensional structures

• Single- and multi-walled

Application CNT in FED

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What is FED?

A field emission display (FED) is a display technology that incorporates flat panel display technology that uses large-area field electron emission sources to provide electrons that strike colored phosphor to produce a color image as an electronic visual display. 

Field emission displays, electrons coming from millions of tiny microtips pass through gates and light up pixels on a screen.

This principle is similar to that of cathode-ray tubes in television sets. The difference: Instead of just one "gun" spraying electrons against the inside of the screens face, there are as many as 500 million of them (microtips).

FED PrinciplesFED Principles

CathodeCathode

The cathode/backplate is a matrix of row and column traces. Each crossover lays the foundation for an addressable cathode emitters.

Each crossover has up to 4,500 emitters, 150 nm in diameter. This emitter density assures a high quality image through manufacturing redundancy, and long-life through low operational stress.

EmissionEmission

Emitters generate electrons when a small voltage is applied to both row (base layer) and column (top layer).

PixelsPixels

Faceplate picture elements (pixels) are formed by depositing and patterning a black matrix, standard red, green, and blue TV phosphors and a thin aluminum layer to reflect colored light forward to the viewer.

Metal TipsMetal Tips

Theory of CNT-FEDTheory of CNT-FED

Field Emission DisplayField Emission Display

Characterised by• Superior mechanical strength (bending modulus 1 TPa)• Low weight• Good heat conductance• Ability to emit a cold electron at relatively low voltages due to high aspect ratios (102–104) and nanometer size tips (1 – 50 nm).

Carbon NanotubeCarbon Nanotube

ATTRIBUTESATTRIBUTES

HIGH RESOLUTIONHIGH BRIGHTNESSLARGE VIEWING ANGLEHIGH WRITING SPEEDSLARGE COLOUR GAMUTHIGH CONTRASTLESS WEIGHT AND SIZELOW POWER CONSUMPTIONLOW COST

The development of Display

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CRT

Cathode Ray Tube

Liquid Crystal Display

Plasma Display Panel

Field Emission Display

LCD

PDP

FED

The LCD is the major display technology, and focused in Japan, Korea and Taiwan.Then, the others nations want to catch this market, the FED is more popular in next five years.

FED advantagesFED advantages

Inherently high luminous efficiency• high contrast levels•  very fast response times• Lower Power Consumption• about half that of an LCD system

– Cold Cathode Emission– Distance between cathode and screen

~0.2–5mm

• Capital investment for manufacturing VLS TV with printable CNT FEDs - 1/10th of LCD

• Cost advantage over LCD could be 40%

Technology Luminous Efficiency (Lm/W)

CRT (at 30KV)

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PDP 0.8

LCD 3

OLED / PLED 5

FED at 8 KV 7

FED Technology RoadblocksFED Technology Roadblocks

• Spindt type FED– Yield problems – Tip wear off, high vacuum – High cost of submicron technology for Spindt

type emitters– High Voltage Breakdown due to electron

bombardment and spacer charging– Phosphor decay in case anode is at low

voltage to counter the above problem – Backscatter from anodes at high anode

voltages leading to cross talk

TECHNOLOGY ATTRIBUTESTECHNOLOGY ATTRIBUTES

Attribute PMLCD AMLCD LCOS PDP FED DLP OLEDSize < 15” <15” < 1” >30” <15” > 60” No limitBrightness nits < 100 <100 <100 <500 <500 <500 >10000Resolution Medium High High High High Medium HighInherent VA Small Small Medium Large Large Large LargeEfficiency lm/w 6 6 - 1 5 6 50Colour gamut Good Good Good Good Good Good GoodManuf. cost Medium V.High High Medium Medium High LowCost pid 1 5 5 1 2 3 <1Market presence Established Established Established Entering ? Established In 2 years

The SEM image of CNT-FED

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Zoom in

Carbon Nanotube Field Emission Display(CNT-FED)

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FED Principle -FOWLER-NORDHEIM THEORY

Emission strongly depends on• Tip height and sharpness• Position in the well

1μm

ITRI Proc Int Disp Workshops VOL.10th;NO.;PAGE.1195-1198(2003)

Mo tip

SEM images showing a triode type FEA with a tip radius ,400 ÅJ. Vac. Sci. Technol. B, Vol. 18, No. 2, MarÕApr 2000

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Features of CNT-FED

Features of CNT-FED：• Ultra Thin Structure• Wide Viewing Angle• See-Through Vision• Light Self Emission• Low Power Consumption• Fast Response Time

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Decrease

1.Deflectiom film

2.Brightness enhancer film

3.Diffusion film

Thanks for you !!