TRANSPARENT ELECTRONICS

the device building block materials, the semiconductor, the electric contacts, and the dielectric layers, must now be invisible – A TRUE CHALLENGE!!

touch display panels, solar cells, flat panel displays, heaters,‘smart windows’

Boom in electronic gadgets

TOUCH PANELS

Transparent Concept Phone

By BloodRabbit, which he thought of while driving home from work.its dimensions are that of a credit cardYou are probably scratching your head andwondering how the electronics and other stuff like a battery and camera fits in but this a very futuristic concept phone

**CLEAR ELECTRONICS MAKE YOUR ROOM APPEAR MORE SPACIOUS BY ALLOWING ELECTRONIC DEVICES TO BE CONSOLIDATED AND STACKED IN SMALL SPACES

**THIS TECHNOLOGY COULD ENABLE THE WINDOWS OR MIRRORS IN OUR HOMES TO BE USED AS COMPUTER MONITORS AND TELEVISION SCREENS

Information displayed on an automobile windshield or surfing the web on the Glass top of the coffee table

3 GOALS TO MOVE AHEAD

the first scientific goal of this technology must be to discover, understand and implement transparent high-performance electronic materials.

The second goal is their implementation and evaluation in transistor and circuit structures.

The third goal relates to achieving application-specific properties since transistor performance and materials property requirements vary, depending on the final product device specifications.

COMBINING OPTICAL TRANSPARENCY WITH ELECTRICAL CONDUCTIVITY

*Transparent insulator possesses completely filled valence band and empty conduction band.

*To become transparent conducting oxide(TCO),these are doped with some oxides In2O3, SnO2, ZnO and CdO to displace fermi level near to the conduction band

TRANSPARENT ELECTRONIC DEVICES

These devices must be chosen,designed ,fabricated and interconnected inorder to construct circuits which have to be simulated and build in such a way that they function appropriately with other circuits

DEVICES CIRCUITS SYSTEMS

PASSIVE LINEAR DEVICES

*Passive device absorb energy, in contrast to an active device which is capable of controlling the flow of energy

*a linear device is distinguished by the fact that its input and output characterstics can be described using linear mathematical relationship

*the three passive linear devices are: **RESISTORS **CAPACITORS **INDUDCTORS

RESISTORS

a)plan-view of linear transparent thin-film resistor(TTFR)

b)A meander TTFR

c) cross-section view of TTFR

CAPACITORS

*TheTTFC capacitance is established by the capacitance density, i.e., the capacitance per unit area,

*a large capacitance density is desired, in order to minimize the size of a capacitor.

* reducing the insulator thickness alsoincreases the capacitance density

INDUCTORS

*The quality factor, Q, is basically an inductorperformance figure-of-merit. A larger Q is better.

*Inductors are useful in resonant circuits and filters. limiting current fluctuations energy storage devices for switched-mode power supplies

*TTFI with good performance appears to be difficult to construct and still challenging

TRANSPARENT THIN-FILM TRANSISTORS(TTFTs)

TTFTs constitute the heart of transparent electronics

a) staggered, bottom-gate since source-drain and gate contacts are located at the top and bottom of the device

b) shows a coplanar, top-gate structure in which the source-drain and thegate are all positioned on the top side of the TTFT

Ideal n-channel transparent thin-film transistor (TTFT) operation

(a) Cut- off. Zero drain current (I D =0)

which is defined by V GS <V ON

(b) Linear, pre-pinch-off.I D is described by Ohm’s law [I D =V DS / R C (V GS )] at low V DS [V DS <<V GS -V ON ]

(c) Nonlinear, pre-pinch-off and, post- pinch-off, saturationV DS =V GS -V ON because of the depletion or ‘pinch- off’

ADVANCEMENTS IN TECHNOLOGY

* TRRAM(transparent resistive random access memory),like cmos device that provides non-volatile memory means data don't get lost when power is off

*TRRAM device is based on an ITO(indium tin oxide) capacitor structure which provides a transmittance of 81%in the visible region of the chip. the data retention is expected to be about 10 years

*RRAM is referred to as “memristor” which could be a new technology where

computer memory is based on resistance instead of electric charge on which flash memory depends.

*products using these approach could become more smaller,faster and cheaper than silicon transistors

Flash memory Flash memory can erase its data in entire blocks, ease in frequent updating of large amounts of data, Inside the flash chip, information is stored in cells. Tunneling electrons pass through a low conductive material to change the electronic charge of the gate "in a flash," clearing the cell of its contents so that it can be rewritten. This is how flash memory gets its name.

The first memory chip “Memristor” mimics the brain,Future flash memory.

*Whose electrical resistance changes when voltage is applied.ReRAM is based on materials

*ReRAM significantly stores more memory and demans less energy and space to store data.It is far more advanced than the current technology.

*does not depend on the diffusion of metallic ions to form conductive paths.

*its resistance changes depending on how much current has passed through it it “remembers” that value even after power is turned off.

*“We’re reaching the limits of what we can do with flash memory in terms of increasing the storage density, and it’s also relatively high power and not as fast as we would like

*“Memristor memory chips promise to run at least 10 times faster and use 10 times less power than an equivalent Flash memory chip,

RRAM v/s flash memory

Continuously variable resistance thatdepends on the last voltage that was applied.This is an important property that allows the device to mimic howneurons in the brain function. Devices that operate in this way are known as ‘memristors’.

MEMRISTOR

*its introduction in 1988 by Toshiba, NAND flash nonvolatile memory has scaled to 1x-nm feature sizes, shrinking cell sizes reduce the number of electronsstored on the floating gate. RRAM provides an alternative.

*in march 2003,researchers at Oregon State University(OSU) builts the world’s First transparent transistor

*A group of scientists at Korea Advanced Institute Of Science And Technology (KAIST) had fabricated a working computer chip that is almost transparent in Dec,2008

*hewletl-packard is the first company which is gonna to to use RRAM TECHNOLOGY in its products from this july

RECENT DISCOVERIES

A NEW REVOLUTION

The team are also exploring using the resistance properties of their material not just for use in memory but also as a computer processor.This versatility will someday replace memory and central processing units(CPUs)with a single chip that can perform both functions.

FUTURE SCOPE

much progress has beenmade in developing new materials and devices for high performance transparentsolar cells, there is still plenty of opportunity to study and improve deviceperformance and fabrication techniques compared with the nontransparent solarcell devices.

FUTURE GADGETS

What we see in science fiction movies are going to be a real working technology and it is not very far,Competition in the world of technology brings us suprising stuffs that we once dreamed of.