M O L E C U L A R E L E C T R O N I C S - A N

I N V I S I B L E Y E T, R E V O L U T I O N A RY

T E C H N O L O G Y

Pre s en ted b y

Ma n i deep r eddy B a dda m

EEE - I V Yea r, B .Tech

SMEC

What actually is MOLETRONICS ?

► It is basically the idea of utilizing

the electronics applications at a

molecular level.

► It is a branch of nanotechnology

that uses single molecules, or

nanoscale collections of single

molecules, as electronic

components.

► Because single molecules

constitute the smallest stable

structures possible, this

miniaturization is the ultimate goal

for shrinking electrical circuits.

Molecular electronics is the study and application of

molecular building blocks for the fabrication of electronic

components.

It is an interdisciplinary area that spans physics, chemistry,

and materials science. The unifying feature is the use of

molecular building blocks for the fabrication of electronic

components.

Due to the prospect of size reduction in electronics offered

by molecular-level control of properties, molecular

electronics has generated much excitement .

Molecular electronics provides a potential means to extend

Moore's Law beyond the foreseen limits of small-scale

conventional silicon integrated circuits.

What is Moore's law ?

Moore’s law was put frothed by Gordon E. Moore, co-founder of the Intel Corporation, who first described the trend in a 1965 paper ‘Cramming More Components Onto Integrated Circuit’ and formulated its current statement in 1975.

The law states that the number of transistors per square inch on integrated circuits had doubled every year since the integrated circuit was invented. Moore predicted that this trend would continue for the foreseeable future.

After four decades, solid-state microelectronics has advanced to the point at which 100 million transistors, with feature size measuring 180 nm can be put onto a few square centimetres of silicon.

His prediction has proven to be accurate, in part because the law now is used in the semiconductor industry to guide long-term planning and to set targets for research and development.

Is the Silicon Integration Technology saturated ?

Will silicon technology become obsolete in future like the value

technology done about 50 years ago? As a scientific pursuit, the search for a viable successor to silicon computer

technology has garnered considerable curiosity in the last decade.

Conventional electronics technology is much indebted to the integrated circuit (IC) technology. IC technology is one of

the important aspects that brought about a revolution in electronics. With

the gradual increased scale of integration, electronics age has passed

through

SSI (small scale integration)-1-12 gates on a single chip

MSI (medium scale integration)-12-30 gates on a single chip

LSI (large scale integration)-30-300 gates on a single chip

VLSI (Very large scale integration)-300-10000 gates on a single chip

ULSI (ultra large scale integration)-beyond 10000 gates on a single chip

What's after ULSI – is it an end to silicon technology ?

The answer to the question is an Obvious one

MOLETRONICS

History of MOLETRONICS

Robert Mullikan & Albert Szent-Gyorgyi proposed study of charge

transfer theory in1940.

In 1974 Mark Ratner & Avi Aviram illustrated a theoretical molecular

rectifier.

Later Avi Aviram detailed a single molecular field effect transistor

in1988.

In 2000 Shirakawa, Heeger and MacDiarmid won Noble prize in physics

for potentially high conductivity of (oxidised) polyacetelene & it

'subsequent development.

The basic question still exists, what materials are the molecular electronics are

made of ?

● ORGANIC POLYMERSDiscovered in mid 1970’s.Polymers are flexible, versatile and easy to process.Behave like a conventional inorganic semiconductor. Does not possess reasonable charge carrier mobility. Mobility obtained in polymers is rather low.Does not demonstrate the existence of controllable band gap of the order of 0.75 to 2 e V.

● POLYPHENYLENE BASED CHAINSThey are capable of carrying currents.They are also capable of switching small currents.Thus, they are used as molecular wires and switches.The current that passes through the molecular-wires is about 30 μA, or about 30 nA per molecule.This works out to about 200 billion electrons per second being transmitted across the short poly phenylene-based molecular wire.

● Aliphatic chain groupsThese basically serve as insulators

● Molecular electronic system

In order to perform as an electronic material, molecules need a set of overlapping electronic states. These states should connect two or

more distant functional points or groups in the molecule.

Conventional electronic devices are traditionally made from bulk materials. The bulk approach has inherent limitations in addition to

becoming increasingly demanding and expensive.

Thus, the idea was born that the components could instead be built up atom for atom in a chemistry lab (bottom up) as opposed to

carving them out of bulk material (top down).

In single molecule electronics, the bulk material is replaced by single molecules. That is, instead of creating structures by removing or

applying material after a pattern scaffold, the atoms are put together in a chemistry lab.

The molecules utilized have properties that resemble traditional electronic components such as a wire, transistor or rectifier

Logic Gate (AND) Logic Gate (OR)

Diode

Switching

Molecular transistor

Prof. Francis Garnier and co-workers, in 1990 developed a total organic transistor known as organic FET.The transistor is a metal insulator semiconductor structure comprising an oxidized silicon substrate and a semiconductor polymer layer. It has great flexibility and can even function when it is bent.

Molecular Memory Chip

Data storage is done by multi porphyrin nanostructures into electronic memory. The application of a voltage causes the molecules to oxidize, or give up electrons. The molecules then retain their positive charge after the electric field is removed, producing a memory effect.

Memory Hold Time

Silicon memory devices retain charged bits for only a millisecond before the charge leaks away. That means that each piece of information must be restored ten to a hundred times a second, which requires substantial amounts of power.

Moletronic device retains its electrons for about nearly fifteen minutes. It has the ability to get the information in and out of the systems and using significantly less power.

Carbon Nanotubes

A second type of molecule that can be used as molecular

wires is the carbon nanotube or “Bucky tube”.

When used on micro patterned semiconductor surfaces, these

nanotube structures make a very conductive wire.

They differ in diameters, chirality and come in a range of

conductive properties ranging from excellent conduction to

pretty good insulation.

The most flexible polyphenylene backbone, is not the most

conductive and the most conductive, the carbon nanotube, is

not the most flexible chemically.

BUCKYPAPER

It is a thin sheet made from an aggregate of carbon nanotubes or carbon nanotube grid paper. The nanotubes are approximately 50,000 times thinner than a human hair. Originally, it was fabricated as a way to handle carbon nanotubes, but it is also being studied and developed into applications by several research groups, showing promise as vehicle armour, personal armour, and next-generation electronics and displays.

Bucky paper is a macroscopic aggregate of carbon nanotubes (CNT), or "Bucky tubes". It owes its name to the buckminsterfullerene, the 60 carbon fullerene (an allotrope of carbon with similar bonding that is sometimes referred to as a "Bucky ball" in honour of R. Buckminster Fuller).

Bucky paper is one tenth the weight yet potentially 500 times stronger than steel when its sheets are stacked to form a composite. It could disperse heat like brass or steel and it could conduct electricity like copper or silicon. Rice University scientist Wade Adams says, "All those things are what a lot of people in nanotechnology have been working toward as sort of Holy Grails.“

APPLICATIONS

• Fire protection: covering material with a thin layer of Bucky paper significantly improves its fire resistance due to the efficient reflection of heat by the dense, compact layer of carbon nanotubes or carbon fibers.

• If exposed to an electric charge, Bucky paper could be used to illuminate computer and television screens. It could be more energy-efficient, lighter, and could allow for a more uniform level of brightness than current cathode ray tube (CRT) and liquidcrystal display (LCD) technology.

• Since individual carbon nanotubes are one of the most thermally conductive materials known, Bucky paper lends itself to the development of heat sinks that would allow computers and other electronic equipment to disperse heat more efficiently than iscurrently possible. This, in turn, could lead to even greater advances in electronic miniaturization.

• Films also could protect electronic circuits and devices within airplanes from electromagnetic interference, which can damageequipment and alter settings. Similarly, such films could allow military aircraft to shield their electromagnetic "signatures", which can be detected via radar.

Advantages

Size

Power

Assembly

Manufacturing Cost

Synthetic flexibility

Durability, Efficiency and Error immunity increases on unimaginable

scale

Tuning of functionality is easier as polymers don’t loose their

characteristics as swiftly as semiconductors

Ever imagined what future looks like with

the help of MOLETRONICS ?

Disadvantages

Controlled fabrication with in specified tolerances.

Hard experimental verification.

CONCLUSION

“The Next Big Thing is very, very small. Picture trillions of transistors, processors so fast their speed is measured in terahertz, infinite capacity, zero cost. It's the dawn of a new technological revolution - and the death of silicon”.