transparent electronics.pptx

7/28/2019 Transparent Electronics.pptx

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TRANSPARENT

ELECTRONICS

-Varsha Anand

1PI09TE121


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INTRODUCTIONIts an emerging science and technology

field focused on producing invisible

electronic circuitry and opto electronic

devices.

This technology basically uses TCOs i.e

Transparent conducting oxides.

These materials are both electrically and

optically conductive.


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COMBININGOPTICALTRANSPARENCY

WITHELECTRICALCONDUCTIVITY

Transparent materials->insulators withfilled valence band and empty conductionband

Conductive materials->filled CB andempty VB

Thus transparent conductors are a

comprise between these two mutuallyexclusive properties.

In InO2 ,SnO2 ZnO ,CdO->these propertiescan be achieved


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To become a TCO ,they have to be

degeneratively doped to displace the fermi

level up to the conduction band.This provides 1.high mobility

2. low optical absorption.

TCOs have

1. High optical transparency. ( Eg>3.1eV)

2. High electrical conductivity.

Therefore Si cannot be used as it has band gap of

1.1eV


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TRANSPARENTELECTRONIC

DEVICES

Transparent electronic

devicesTransparent Passive devices

Transparent Active devices


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PASSIVEDEVICES

Transparent Passive devices

Transparent Thin Film Resistors(TTFR)

Transparent Thin Film Capacitors(TTFC)

Transparent Thin Film Inductors(TTFI)


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Transparent Thin Film Resistors


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TRANSPARENT THIN FILM RESISTORS

Resistive material: ITO(indium tin oxide)Typical sheet resistance: 10 to 10^5 ohm/sq

Operated at relatively low frequencies so that

the effect parasitic inductances are absentThey are fabricated on insulators so that the

effect parasitic capacitances are absent

Conductivity depends on number of oxygenvacancies.


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TRANSPARENT THIN FILM CAPACITORS


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TRANSPARENT THIN FILM CAPACITORS

Most insulators are transparent

Contact layers are made of highly

conducting TCOs (ITO)

C=A/d

To reduce capacitor size high k dielectric

must be used and also thickness can be

reduced to increase capacitance.


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TRANSPARENTTHINFILMINDUCTORS

It has relatively poor conductance of

TCOs compared to metal

Transparent magnetically permeable

insulator is not known yet!! Therefore it

has parasitic resistance associated with it.

It has low quality factor Q .

In spite of demerits a transparent

microwave antenna being constructed is

reported .


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TRANSPARENT THIN FILM TRANSISTORS

Constitutes the heart of transparent electronics

Channel is formed from highly insulating, wide bandgap transparent semiconductor(ZnO).

Source, drain and gate contacts are made fromhighly conductive TCO (ITO).

Two possible configurations are:

Bottom gate

Top gate


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TTFT


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Possible structure, (a) Bottom gate,

and

(b) Top gate.


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OPERATIONOFABOTTOMGATE TFT


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Strengths and Weaknesses

Strengths Weaknesses

Visible transparency High resistance of TCOs

Large area Lack of complementary devices

Low cost (solution based

deposition and printing)

Low temperature processing Technological immaturity

Free real estate

Passive availability (R & C)

Robust stable inorganic materials

Safe, nontoxic materials


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APPLICATIONS

Active Matrix LCD (AMLCD).

Active Matrix Organic Light Emitting Device display

backplane (AMOLED).

Value added glass.

Transparent electronics on opaque substrates.


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UV detectors and arrays

Transparent solar cells

UV detectors for spectrally resolved

imaging.

Security applications:

Invisible cameras and

Invisible RFIDs


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FUTURE SCOPE

Research is going on for developing high

performance transparent solar cells

If transparency of solar cells is achieved at

a specific light band, it will lead to new

applications such as solar windows.

Thus energy is conserved and pollution

reduces.


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Thank you

transparent electronics.pptx

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