51639309 Molecular Electronics Abstract

8/2/2019 51639309 Molecular Electronics Abstract

1/26

Molecular Electronics Seminar Report 03

1. INTRODUCTION

Will silicon technology become obsolete in future like the value technology

done about 50 years ago? Scientists and technologists working in anew field of

electronics, known as molecular electronics is a relatively new field, which emerged as

an important area of research only in the 1980s. It was through the efforts of late

professor Carter of the U.S.A that the field was born.

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), MSI (medium scale integration), LSI

(large scale integration), and ULSI (ultra large scale integration). These may be

respectively classified as integration technology with 1-12 gates, 12-30 gates, 30-300

gates, 300-10000 gates, and beyond 10000 gates on a single chip.

The density of IC technology is increasing in pace with Famous Moores law of

1965. Till date Moores law about the doubling of the number of components in an I.C

every year holds good. He wrote in his original paper entitled Cramming More

Components Onto Integrated Circuit , that, the complexity for minimum component

costs has increased at the rate of roughly a factor of 2 per year. Certainly, over the short

term, this rate can be expected to continue, if not to increase. Over the longer term, the

rate of increase is a bit more uncertain, although there is no reason to believe that it will

not remain constant for at least ten more years.

Dept. of EEE MESCE, Kuttippuram1


2/26


It is now over 30 years since Moore talked of this so called technology-mantra.

It is found that I.Cs are following his law and there is a prediction that Moores law

shall remain valid till 2010.the prediction was based on a survey of industries and is

believed to be correct with research of properties of semiconductors and production

processes. But beyond ULSI, a new technology may become competitive to

semiconductor technology. This new technology is known as Molecular electronics.

Semiconductor integration beyond ULSI, through conventional electronic technology is

facing problems with fundamental physical limitations like quantum effects etc.

Molecular based electronics can overcome the fundamental physical and economic

issues limiting Silicon Technology.

For a scaling technology beyond ULSI, prof. Forest Carter put forward a novel

idea. In digital electronics, YES and NO states are usually and respectively

implemented and/or defined by ON and OFF conditions of a switching transistor.

Prof. Carter postulated that instead using a transistor; a molecule (a single molecule or a

small aggregate of molecule) might be used to represent the two states, namely YES &

NO of digital electronics.

For e.g. one can use positive spin & negative spin of a molecule to represent

respectively YES & NO states of binary logic. As in the new concept a molecule

rather than a transistor is proposed to be used, the scaling technology may go to

molecular scale. It is therefore defined as MSE (molecular scale electronics). MSE is far

beyond the ULSI technology in terms of scaling. In order to augment his postulation

Prof. Carter conducted a number of international conferences on the subject. The

outcome of these conferences has been to establish the field of molecular electronics.



3/26


However, as of today, molecular electronics is a broad field. The field is a result

of a search for alternative materials, devices and applications of electronics. The field

deals with organic materials. The field is a challenge but not a replacement for inorganic

electronics on immediate terms. Molecular electronics is a technological challenge to

explore the possible application of organic materials, non-linear optics and biologically

important materials in the field of electronics. Therefore hopes run high for realization

of plastic electronic systems, all optical computers, and chemical or bio-computers with

inbuilt thinking functions and biochips etc.

In the field of communication the role of optical soliton, which is a by-product

of non-linear optics, will be used in the implementation of a very haul (say 50,000

kilometers) with T bits/sec data rate networks. Economic solar cells are another existing

promise of molecular electronics.

Molecular electronics, which is a high investment and high-risk field, is at the

same time a highly promising one. High investment and risks are involved in the initial

phases. Under commercial phases the cost molecular systems shall be cheaper. The

prospects of molecular electronics depend on the successful interaction and coordination

of scientists of diverse fields like computer, electronics, physics, chemistry, biology,

material science, etc.

Historically the concept of molecule electronics dates back to the last century.

The familiar e.g. is the use of organic materials in displays of watches and calculators.

During the 1950, material scientists started working on organic solids as alternative

semiconductors because of their attractive optical properties. Research the started in



4/26


Soviet Union, Japan, U.K, France, Germany and U.S.But Forest Carter who conducted

in 1980s a number of international conferences on the subject mainly initiated the

interest in molecular electronics as a separate and special subject. Since then although

the progress of molecular electronics has always been smooth, the prospects of the

future have vastly improved.



5/26


6/26


Typical resistivity

Here it can be pertinent to mention the functioning of p-n junction. The solid

state error of electronics owes much to the discovery of p-n junction, which is based on

the flow of electricity through silicon. The flow of electricity can be controlled by

adding impurities to silicon.

Mobilities are seen to be low in molecular organic materials. Polymers took a

leading high mobility charge carriers. But while some of these are insulators and cannot

be doped, others are too impure and too inhomogeneous to access experimental high

mobilities. Despite this, the conjugated or conducting polymers exhibited high carrier

mobilities when doped. Several experiments confirm that synthesized conducting

polymers could be employed as either metallic or semi conducting component of a

metal-semiconductor junction device such as Schottky and p-n junction diode, with

rectification ratios in excess of thousands



7/26


There are reports of polymer based MISFET (metal insulator semiconductor

field effect transistor) devices with mobilities as high as 0.1 cm sq / volt sec, total

organic (polymer) transistor and LED with quantum efficiencies in the region of 1%

photons per electrons. Organics, which are intrinsically p-type in semi conducting

behavior, have been widely experimented with conjugated polymers.

There are recent reports of n-type organic semiconductors. This behavior is

found when T N C Q (tetracyanoquinodimethane) is used as the active semi conducting

materials in MISFETs. The maximum field mobility has been observed as 3x10-5 cm sq

/ volt sec.

An active polymer transistor was first reported by Burroughes et al in 1988. The

device had some important features such as no chemical doping or side reactions and

insensitivity to disorder. But the operating frequency was low due to low carrier

mobility.

However Prof. Francis Garnier and co-workers achieved a dramatic lead in

1990. They reported 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. The operating speed is still poor. There are also reports of organic FET from

Dr.Friend and co-workers Cavendish Laboratory of Cambridge. All FETs reported so

far show a poor current and a power handling capability in comparison with inorganic

FETs, in addition to low operating frequency. These problem need to be address before

organic FETs can be used in place of inorganic FETs.



8/26


Recently, pure semi conducting polymers have channeled into display devices.

These conjugated with improved impurity have shown very strong photoluminescence.

The most exciting news is the possibility that conjugated polymers would be used to

manufacture LEDs out of plastic. This has immense application computer and TV

screens.

To provide pixelled large area flat screen displays, two stumbling blocks, which

are yet to be overcome, are efficiency and lifetime. LEDs should have at least 10%

efficiency before they can be used in commercial areas. On the other hand, where as a

minimum of 10000 hrs lifetimes is required for flat screen or panel displays till date, the

maximum life of polymer LEDs is reported to be only 1000 hrs.

Organic materials have not being able to compete with silicon or inorganic

materials to form active electronic devices. Moreover, the materials to be studied, if at

all, are yet to be finalized. But there is a worldwide trend towards organics, at least in

research areas.

Two of the molecules that have been used to demonstrate current carrying

molecular scale structures are poly phenylene-based chains and carbon nanotubes.



9/26


3. POLYPHENYLENE-BASED CHAINS

Polyphenylene based molecular wires and switches use chains of organic

aromatic benzene rings. Recently, it has been shown by several research groups that

molecules of this type conduct electrical currents. In addition, polyphenylenes as well

as similar organic molecules have been shown to be capable of switching small currents.

An individual benzene ring less one of its hydrogens, giving the phenyl group

C6H5, can be bonded as a group to other molecular components. By removing two

hydrogens, giving the group C6H4, you have two binding sites in the ring.

Polyphenylenes are obtained by binding phenylenes to each other on both sides

and ending the chain-like structures with phenyl groups obtain Polyphenylenes. These

can be made in different shapes and lengths. Other types of molecular groups (e.g.,

singly-bonded aliphatic groups, doubly-bonded ethanol groups, and triple bonded

ethanol or acetylene groups) may be inserted into a Polyphenylene chain to make

Polyphenylene-based aromatic molecules with useful structures and properties.

Recently, sensitive experiments by various investigators have shown that Polyphenylene

based molecules conduct electricity. In one experiment, an electrical current was passed

through a monolayer of approximately 1,000 Polyphenylene-based molecular wires that

were arranged in a nanometer-scale pore and adsorbed to metal contacts on either end.

The system was prepared so that all the molecules of the nanopore were identical

three benzene-ring polyphenylene-based chain molecules. The measured current that

passed through the molecular-wires was 30 A, or about 30 n A per molecule. This



10/26


works out to about 200 billion electrons per second being transmitted across the short

polyphenylene-based molecular wire.

For comparison, a larger molecule, the carbon nanotube (bucky tube) has been

measured transmitting currents in the range 20 to 500 n A, or 120 billion to 3 trillion

electrons per second. The polyphenylene-based molecular-wires do not carry as much

current as the bucky tubes however, because of their very small cross-sectional areas;

their current densities are the same as those of the carbon nanotubes. These current

densities are quite high - about a half a million times greater than that of a copper wire.

Polyphenylene-based molecules also have the advantage of a well-defined

chemistry, synthetic flexibility, and more than a century of experience studying and

manipulating them. J.M. Tour who has made mole quantities of these molecules has

refined the synthetic techniques for conductive polyphenylene-based chains. These

Polyphenylene-based chains have come to be known as Tour wires". The way energy

is transferred or channeled from one end of a molecule to the other is via p-type orbital

lying above and below the plane of the molecule. These p-type orbital can extend over

the length of the molecule thus connecting with the neighboring molecule creating a

polyphenylene-based chain. Polyphenylenes will conduct current as long as

conjunction among p-bonded components is maintained. Polyphenylene-based

molecules bonded with multiply bonded groups (such as ethenyl, -HC=CH-, or ethynyl,

-C=C-) are also conductive. Because of this, triply bonded ethynyl or acetylenic

linkages can be inserted as spacers between phenyl rings in a Tour wire. Spacers are

needed to eliminate steric interference between hydrogen atoms bonded to adjacent

rings. Steric interference can affect the extent of p-orbital overlap between adjacent

rings thereby reducing conduciveness.



11/26


4. CARBON NANOTUBES

A second type of molecule that can be used for a molecular electronic backbone

is the carbon nanotube or bucky tube. When used on micropattened semiconductor

surfaces, these carbon nanotube structures make a very conductive wire. They differ in

diameters and chiralities and come in a range of conductive properties ranging from

excellent conduction to pretty good insulation. Bucky tubes are fairly new to the world

of chemistry having only been discovered and characterized in the last two decades. It

is not yet known how to selectively make a particular structure while excluding others.

Once made, carbon nanotubes are stable but they are made only under extreme

conditions. Their synthesis is neither selective nor precise. During synthesis many

molecules form in a range of structures. To get the precision required to function in

electronic circuits, the use of physical inspection and manipulation of the molecules,

one at a time, is needed. So far, there is no bulk chemical method for this purpose.

Currently, the molecular electronic community is in a situation where the most

chemically flexible molecular backbone, the polyphenylene backbone, is not the most

conductive and the most conductive, the carbon nanotube, is not the most flexible

chemically.

Development has been undertaken by several researchers on a variety of

molecular electronic components for use in molecular circuits. Here, two particular

components, aliphatic molecular insulators and diode switches, that in concept can be

used with Tour wires to build the computational devices are focused on.



12/26


Aliphatic Molecular Insulators

Aliphatic organic molecules have nodes in their electron densities above the

atomic nuclei. For this reason, they cannot transport unimpeded electrical current when

placed under a voltage bias. This enables aliphatic molecules or groups to act like

resistors.

Diode Switches

A diode is a two terminal device in which current may pass in one direction

through the device, but not the in the other direction, and in which the conduction of

current may be switched on or off. Two important types of molecular-scale diode

switches have been demonstrated: rectifying diodes and resonant tunneling diodes.

Both are modeled after familiar solid-state analoges.

Rectifying Diodes

Rectifying diodes, also called molecular rectifiers, use structures that make it

more difficult for an electric current to go through them in one direction, usually termed

reverse direction from terminal B to A, than it is to go the opposite forward

direction from A to B. Rectifying diodes have been elements of analog and digital

circuits since the beginning of the electronic revolution. They have also had a role in

the forming and testing of strategies for molecular scale electronics. In fact, the first

theoretical paper on molecular electronics was a paper entitled Molecular Rectifiers

by A. Aviram and M.A. Ratner that appeared in the journal Chemical Physics Letters in

November 1974. But it was only in 1997 that, building on earlier experiments; two

separate groups demonstrated practical molecular rectifiers. R.M. Metzger at the

University of Alabama led one group and the other led by M.A. Reed at Yale

University.



13/26


Resonant Tunneling Diodes (RTDs)

Unlike the rectifying diode, current can pass just as easily in both directions

through an RTD. The RTD uses electron energy quantization to permit the amount of

voltage bias across the source and drain to control the diode so as to switch current on

and off, and so as to keep electrical current going from the source to the drain. An

experimental RTD of a working electronic device has been recently synthesized by Tour

and demonstrated by Reed. The device is a molecular analog of a larger solid-state

RTD that has commonly been fabricated in III-V semiconductors and used in solid-

state, quantum-effect circuitry.

Advantages Of Polyphenylene-Based Structures

With Polyphenylene-based molecules, it is relatively easy to propose complex

molecular structures that are needed for digital logic and to know ahead of time that the

needed structures can be synthesized. For their size, polyphenylene-based molecular

devices conduct an impressive current of electrons.

Tour-wire-based molecular digital logic has another advantage. Since

polyphenylene-based molecules are so much smaller than carbon nanotubes, when

electronic logic structures are finally synthesized and operated, they will represent the

ultimate in digital electronic logic miniaturization. Any other structure will likely be as

large or larger. It is unlikely that any working structure will be smaller.



14/26


5. REALIZATION OF BASIC CIRCUITS

Molecular AND and OR Gates Using Diode-Diode Logic

The circuits for the AND and OR digital logic gates which use diode-diode

logic structures have been known for decades. Molecular logic gates constructed from

the selected diode molecule would measure about 3 nm x 4 nm. That area is about one

million times smaller than would be the area of a corresponding semiconductor logic

element.

Molecular XOR Gates Using Molecular RTDs and Molecular

Rectifying Diodes

To complete the diode-based family of logic gates, you need a NOT gate. To

make a NOT gate with diodes, you need to use resonant tunneling diodes. Using a

Reed-Tour molecular RTD and two polyphenylene-based rectifying diodes, an XOR

gate measuring about 5 nm x 5 nm can be built. The three switching devices used are

built with polyphenylene-based Tour wire backbones. Except for the insertion of the

molecular RTD, the molecular circuit for the XOR gate is similar to the OR gate. The

XOR and OR gates operate alike except when the XOR gates inputs are 1 (i.e., a high

voltage) at both inputs. This shuts off current flow through the RTD and makes the

XOR gates output 0, or low voltage. With the XOR gate added to the AND and OR

gates, you have a complete set which can be made the same as the complete set AND,

OR, and NOT.



15/26


Molecular Electronic Half Adder

With a complete set of molecular logic gates, larger structures can be made that

implement higher binary digital functions. An electronic half adder can be built using

Tour wires and molecular AND and XOR gates and measuring only 10 nm x 10 nm.

When currents and voltages representing two addends are passed through the molecular

half adder, they will be added electronically. The half adder has two inputs that split the

current introduced so that the current passes through both of the logic gates regardless

of which input receives the current. Results from the AND and XOR gates are

delivered to separate outputs. By using an out-of-plane connector structure, an in-plane

molecular wire can be passed over making it possible to connect the gates. Even though

the input to each molecular lead is split, signal loss should not be a problem because the

signal is recombined on the output side of the structure. In our half adder design, a

three-methylene aliphatic chain resistor is embedded in the output lead that goes to the

ground to help minimize signal loss.

Molecular Electronic Full Adder

By combining two half adders plus an OR gate, you can make a molecular

electronic full adder measuring about 25 nm x 25 nm.

Combining Individual Devices

By bonding together existing functional devices, it is thought that devices of

higher functions can be made. But when put together, these individual molecular

devices will not behave as they do by themselves. The characteristic properties of each

device will in general be altered by the quantum wave interference from the electrons in

the devices. It is expected that Fermi levels will be affected as well. Software is being

developed to deal with quantum mechanical issues so that complete molecular

electronic circuits may be understood and built.



16/26


6. CHARACTERISTICS OF MOLECULAR DEVICES

Nonlinear I-V Behavior

Unlike solid-state electronics, the I-V behavior of a molecular wire is nonlinear.

Some molecular devices will take advantage of this nonlinearity.

Energy Dissipation

When electrons move through a molecule, some of their energy can be lost to

other electrons motions and the motion of the nuclei of the molecule. The amount of

energy lost depends on the electronic energy levels of the molecule and how they

interact with the molecules vibrational modes. Depending on the mechanism of

conductance, the energy loss can range from very small to significantly large.

Gain in Molecular Electronic Circuits

In large molecular structures deploying molecular devices with power gain, such

as molecular transistors, there will be a need to restore signal loss. Gain is needed in

order to achieve signal isolation, maintain signal-to-noise ratio, and to achieve fan-out.

Speeds

Energy dissipation relates closely to the speed at which a molecular electronic

circuit can operate. If strong couplings cause the signal-to-noise ratio to dramatically

decrease, a greater total charge flow would be needed to ensure the reading of a bit.

This would require more time. Because of their scale and density, molecular electronic



17/26


computers may not need to be faster than semiconductor computers to be highly

important. The molecular half-added described earlier is one million times smaller than

one in a Pentium processor.

Optical information technology

The ever growing demand of increased computing speed is mainly limited by

memory accessing time and storage capacity. Optical storage and accessing can remove

these problems, as optical speed is the ultimate speed.

Photo chromic materials show a bistable property. They undergo reversible color

changes under irradiation at an appropriate wavelength. The photon absorption

technique of photo chromic material, in order to build a three-dimensional optical

memory, appears appropriate to build a three-dimensional optical memory. Applications

of electronic materials in displays and optical filters have also been conceptualized.

With the advent of optical fiber communication an interest in components for

processing optical signals has arisen. On the other hand, in order to avoid the drawbacks

of conventional electronics IC technology such as problems of parasitic capacitance,

inductance and resistance, less reliability and power dissipation there has arisen the need

to use optical integrated circuits (OICs) in proposed all optical computers where full

advantage of the fundamental speed of light is proposed to be achieved.

Nonlinear optics (NLO) is a new frontier of science and technology, multi-

disciplinary in nature, which has potential applications in computer communication and



18/26


information technology. Current research has made available organic NLO materials

with properties superior to those of inorganic NLO materials. Discovery of laser in

1960s has given a thrust to the research of NLO materials and their applications.

Nonlinearity can be used basically in two ways for electronic devices: frequency

conversion and refractive index modulation. Frequency conversion technique which is

due to second order linearity, may be used for second harmonic generation, frequency

mixing and parametric amplification, etc. the prime interest of second harmonic

generation is for optical data storage.

Molecular Scale Electronics

The quest forever decreasing size but more complex electronic component with

high speed ability gave birth to MSE. The concept that molecules may be designed to

operate as self constrained devices was put forward by Carter, who proposed some

molecular analogues of conventional electronic switches, gates and connections.

Accordingly a molecular p-n junction gate was proposed by Aviram and Rather. MSE is

a simple interpolation of IC scaling. Scaling is an attractive technology. Scaling of FET

and MOS transistors is more rigorous and well defined than that of bipolar transistors.

Silicon technology has offered us SSI, LSI, VLSI and finally we have ULSI.

Such technologies make even the logic gate minimization technique redundant. Today

integration barrier of 2.5 million transistors on a chip is over. But there are some

problems now in further scaling in silicon technology. For instance, power dissipation

and quantum effect are posing problems for increasing packing density.



19/26


MSE is a remedial measure. Molecules possess great variety in the structure and

properties. Therefore finding molecules and their appropriate properties for electronics,

opto-electronics and bio-electronics is possible the study of a single molecule is not a

problem now as we have STM (scaling tunneling microscope), AFM (atomic force

microscope),L-B technique etc.



20/26


7. FUTURE DEVELOPMENTS

At some of the top laboratories around the country, scientists are publicly

expressing beliefs that before now they would only express in private: electronics

technology is on the edge of a molecular revolution where molecules will be used in

place of semiconductors, creating electronics circuit small that their size will be

measured in atoms not microns. They are boldly predicting that the impact on

computing speed and memory resulting from circuits so small would stagger virtually

all fields of technology and business.

Research teams from Rice and Yale Universities say that they have successfully

created molecular size switches that can be opened and closed repeatedly. The

HP/UCLA group had only reported being able to switch once, not repeatedly. Repeated

switching is necessary to build functioning digital computers. These breakthroughs in

the field of molecular electronics seem to be giving researches a new sense of

confidence.

There are several research groups working in laboratories under top-secret

conditions. They are making progress on several fronts. One of them is said to be

working on molecular scale Random Access Memory (RAM). RAM, on a molecular

scale, could offer incredibly huge storage capacities. Molecular methods could make it

available at costs so low as to be pocket change. Because of the very small scale of such

devices, it might be possible to store, for e.g., a DVD movie on something the size of a

grain of rice.



21/26


The micro electronic devices on todays silicon chips have components that are

0.18 microns in size or about one thousandth the width of a human hair. They could go

as small as 0.10 microns or hundred nanometers. In molecular electronics, the

components could be as tiny as 1 nanometer. This would make for a new breed of super

powerful chips and computers so small that could be incorporated into all manmade

items.

The semiconductor world predicts it will continue to advance the silicon-based

chip, making ever-smaller device, through the year 2014. But the costs involved with

these advancements are enormous. Currently semiconductor chips are made in

multibillion-dollar fabrication plants by etching circuitry into layers of silicon with light

waves. Its a very expensive process and each new generation requires huge amounts of

money to upgrade to newer fab-plants. The world of computers is in for a change.

Several computer semiconductor companies, including Sun Microsystems and

Motorola have been meeting to consider forming a consortium that would look for

commercial uses for molecular electronics. Researches say that this is still only the

beginning in the making of molecular computers. There are still many obstacles to over

come before molecular computers become reality.

Some researches believe that in order for molecular systems to work as

computers, they will need to have fault tolerant architectures. Several groups are

working on such devices. The progress made recently has caused a lot of excitements

among researches in molecular electronics. For a long time, they have had the vision but

have had few results. Now they are looking towards the future and have results that are

helping to map the way for them.



22/26


8. CONCLUSION

The subject of molecular electronics has moved from mere conjuncture to an

experimental stage. Research in molecular electronics will naturally dominate the next

century.

Today is the age of information explosion. Polymer materials hold hopes of

rapid development of improved systems and techniques of computing and

communicationsthe two wings of information technology. For e.g., polymer optical

fiber has a number of advantages over glass fibers like better ductivity, light weight,

higher flexibility is in splicing and insensitivity to stresses etc. all these show that

polymers will play a vital role in the coming years and MSE shall compete with IC

technology which is growing in accordance with Moores prediction.



23/26


9. REFERENCES

"Large-scale synthesis of carbon nanotubes", T W Ebbesen and P M Ajayan

Nature, vol.358, p220 (1992

Scientific forum http://www.calmec.com/scientif.htm

Search http://www.calmec.com/search.htm

www.ieee.org



24/26


CONTENTS

1. INTRODUCTION 1

2. ORGANIC DEVICES 5

3. POLYPHENYLENE-BASED CHAINS 9

4. CARBON-NANOTUBES 11

5. REALIZATION OF BASIC CIRCUITS 14

6. CHARACTERISTICS OF MOLECULAR DEVICES 16

7. FUTURE DEVELOPMENTS 20

8. CONCLUSION 22

9. REFERENCES 23



25/26


ACKNOWLEDGEMENT

I express my sincere gratitude to Dr.Nambissan, Prof. & Head,

Department of Electrical and Electronics Engineering, MES College of

Engineering, Kuttippuram, for his cooperation and encouragement.

I would also like to thank my seminar guide Ms. Sunitha M.M.

(Lecturer, Department of EEE), Asst. Prof. Gylson Thomas. (Staff in-charge,

Department of EEE) for their invaluable advice and wholehearted cooperation

without which this seminar would not have seen the light of day.

Gracious gratitude to all the faculty of the department of EEE &

friends for their valuable advice and encouragement.



26/26


ABSTRACT

Semiconductor integration beyond Ultra Large Scale Integration (ULSI),

through conventional electronic technology facing some problems with fundamental

physical limitations. Beyond ULSI, a new technology may become competitive to

semiconductor technology. This new technology is known is as Molecular Electronics.

Molecular based electronics can overcome the fundamental physical and

economic issues limiting Si technology. Here, molecules will be used in place of

semiconductor, creating electronic circuit small that their size will be measured in

atoms. By using molecular scale technology, we can realize molecular AND gates, OR

gates, XOR gates etc.

The dramatic reduction in size, and the sheer enormity of numbers in

manufacture, are the principle benefits promised by the field of molecular electronics.

Documents

51639309 Molecular Electronics Abstract