Republic of Yemen الجمھورية اليمنية

Sana'a University جامعة صنعاء

Faculty of Engineering كلية الھندسة

Electrical Engineering Department ھندسة الكھربائيةقسم ال

communication Section شعبة ا3تصا3ت

Nanoelectronics

Prepared by:

Mahmoud Nasooh Naser Alqousi (460/2012)

Supervisor:

Dr.Abdullsalam Al-Kholidi

CONTENTS

ABSTRACT 1

1. Introduction 1

1.1 Nanoelectronics 1

1.2 Foundemental concepts 2

1.3Approaches to nanoelectronics 2

1.3.1 Nanofabrication 2

1.3.2 Nanomaterials electronics 2

2. Reducing transistor size 3

2.1 Nanowire FET 3

2.2 Quantum dots transistors 3

4. Nanoelectronics applications 4

5. Limitations of nanoelectronics 6

6. Conclusion 6

REFERENCES 6

1

Abstract

The last few decades has seen an exponential growth in the electronic devices capabilities

due primarily to a decrease in the size of the transistors and therefore the ICs on these

devices . Nanoelectronics holds the promise of making electronic devices more powerful

than are possible with conventional semiconductor fabrication techniques. our goal in this

work is to understand the meaning of nanoelectronics , and to study and explain the

approaches used by nanotechnology researchers to make smaller transistors and therefore

smaller electronic devices , also to give some applications of the nanoelectronics for

some important fields , and discuss the limitations associated with it.

Keywords: electronic devices capabilities , nanotechnology, nanoelectronics ,

fabrication , integrated circuits (ICs) , transistors .

1.Introduction :

Electronic devices have seen a sustained exponential decrease in size and cost and a

similar increase in performance and level of integration over the last thirty years , this is

mainly due to the decrease in the transistors size [1], since the transistors are the basic

elements of building all ICs , CPUs and memory storage chips .

The resulting doubling of transistors number every 18 months (known as Moores Law) is,

however, expected to break down for conventional microelectronics in about 15 years for

both fundamental and economic reasons . The search is on, therefore, for new solutions to

reduce the transistors size and the electronic devices. One of the promising solutions is

the use of nanotechnology in the electronics field .

1.1 Nanoelectronics :

Nanoelectronics refer to the use of nanotechnology concepts and techniques in electronic

components. So these electronic components, especially transistors, employ

nanotechnology to take advantage of the novel properties enabled by the nanoscale. [2].

In 1965 Gordon Moore observed that silicon transistors were undergoing a continual

process of scaling downward, an observation which was later codified as Moore's law.

Since his observation transistor minimum feature sizes have decreased from 10

micrometers to the 28-22 nm range in 2011. The field of nanoelectronics aims to enable

the continued realization of this law by using new methods and materials to build

electronic devices with feature sizes on the nanoscale.

2

1.2 Fundamental concepts : The nanometre scale is about a billionth of a metre

and things this small can behave quite weirdly.

These unusual physical and chemical

characteristics come about because there is an

increase in surface area compared to volume (as

illustrated in Figure 1 . as particles get smaller and

also because they are subject to quantum effects.

This means they can behave in different ways and

do not follow the same laws of physics that larger

objects do [3].

1.3 Approaches to nanoelectronics :

There are several ways in the the design and manufacture of

devices at nanoscles . these the two most important

Approaches:

1) Nanofabrication :

Nanofabrication is the design and manufacture of devices with

dimensions measured in nanometers. One nanometer is

10 -9 meter, or a millionth of a millimeter. Nanofabrication is of

interest to computer engineers because it opens the door to

super-high-density microprocessors and memory chips. It has

been suggested that each data bit could be stored in

single atom as shown in Figure 2.

2) Nanomaterials Electronics :

Nanomaterials are defined as materials with at least one external dimension in the size

range from approximately 1-100 nanometers [4] .

So the Nanomaterials can be used to implement the desired structures for different

electronic applications for example :

Nanowires and nanotubes are used to produce MOSFET transistors that are very small

and very efficient .

Figure 1. Surface Area to Volume Ratio

Figure 2. Schematic of the single-atom

transistor

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2. Shrinking Transistors size using nanotechnology :

The importance of reducing transistor size comes from the fact that transistors are the

basic elements for building all kind of electronic devices in this age for example :all kind

of CPUs are essentially a huge arrangement of these transistors , also transistors are used

to build all kind of logic circuits (simple or complex) which are used to build all kind of

ICs such as (encoders and decoders),(multiplexers and de multiplexers) and so on [5,6].

Also they are used to build the registers and other kind of memories .

there are some ways available to accomplish this by using nanotechnology :

1) nanowire FET :

Using a nanowire as the channel of the

FET is a method that researchers are

exploring to make even more progress in

reducing current leakage. A nanowire

transistor is shown in Figure 3.

It consists of a nanowire made of

semiconducting material connecting the

source and drain of the transistor, with a

gate controlling the current flow through the

nanowire.

Using a nanowire as the channel allows you to

completely wrap the gate around the channel.

This should allow the voltage applied to the gate

to have even more control over the channel than

when using the finFET. This vertical structure

also saves space, allowing a higher density of

transistors on a chip. Millions or billions of

vertical nanowires could be grown on a

substrate as shown on the Figure 4.

2) Quantum dots transistors :

Researchers have demonstrated that they can build

transistors in which quantum dots form the channel through which current flows. .

That channel can be as small as 4 nanometers.

Figure 3 . The structure nanowire FET.

Figure 4 . Array of nanowire transistors

4

3. Applications of nanoelectronics :

Nenoelctronics have enormous number of applications in all kind of electronic devices

and it touches all aspects of life , some of these applications are still under

experimentation and others had been produced and are already in use in our life .

we are considering below some of the most important applications :

1) Memory Storage : Electronic memory designs in the past have largely relied

on the formation of transistors. However, research

into nano electronics have offered an alternative using

reconfigurable interconnections between vertical and

horizontal wiring arrays to create ultra high density

memories. Two leaders in this area are Nantero which has

developed a carbon nanotube based crossbar memory

called nano-RAMs .as shown in Figure 6 . and Hewlett-

Packard which has proposed the use of memristor material as

a future replacement of Flash memory.

2) Displays : The production of displays with low energy consumption

might be accomplished using carbon nanotubes (CNT) which

shown in Figure 7. Carbon nanotubes are electrically

conductive and due to their small diameter of several

nanometers, they can be used as field emitters with extremely

high efficiency for field emission displays (FED). The

principle of operation resembles that of the cathode ray tube,

but on a much smaller length scale [8]. Also it makes it

possible to manufacture larger and more flexible OLED

displays.

3) Quantum Computers : Entirely new approaches for computing exploit the laws of

quantum mechanics for novel quantum computers, which

enable the use of fast quantum algorithms. The Quantum

computer has quantum bit memory space termed "Qubit" for

several computations at the same time. This facility may

improve the performance of the older systems . Figure 8

Shows a possible picture for the quantum computers in the

future.

Figure 6 . nano-RAMs [7]

Figure 7. nanotubes shape

Figure 8. Quantum Computers

5

4) Radios : A nanoradio is considered as the Smallest Radio Receiver in

the World , it’s basicly a radio receiver or transmitter

constructed on a nanometer scale. Currently only receivers

have been developed and they are structured around

a carbon nanotube . Figure 9 gives a simplified model of the

nanoradio [10] .

5) Energy Production : Research is ongoing to use nanowires and other nanostructured materials with the hope to

create cheaper and more efficient solar cells than are possible with conventional planar

silicon solar cells [11]. It is believed that the invention of more efficient solar energy

would have a great effect on satisfying global energy needs.

6) Medical Diagnostics : There is great interest in constructing

nanoelectronic devices that could detect the

concentrations of biomolecules 1 in real time for

use as medical diagnostics, thus falling into the

category of nanomedicine. A parallel line of

research seeks to create nanoelectronic devices

which could interact with single cells for use in

basic biological research. These devices are

called nanosensors as shown in Figure 10 [12] .

Figure 10. nanosensores

Figure 9. simplified model of

nanoradio

1 An organic compound normally present as an essential component of

living organism.

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4. Limitations of nanoelectronics : [13,14]

1) Temperature:

Constantly breaking and reforming bonds as well as the friction caused by millions

of nanobots is likely to produce a large amount of heat.

2) Efficiency:

Sure machines are versatile but because they work on such a small scale they may run

into issues competing with other technologies .

3) Material Limitations:

Another problem with nanotechnology is the scale it works on: small, highly complex

nanomachines are probably awesome at building things with carbon, but uranium weights

about 20 times more and is radioactive.

4) Non-static objects:

The problems in trying to synthesize livings things as already been discussed so I won't

go into it again.

5) Uncontrolled environment:

Nanites would likely have a hard time building something in a hostile environment. Your

workforce might be billions of tiny robots strong but in a martian sandstorm they will

likely be unable to finish the job

6) Resources Required:

Given that a maker does not make something out of nothing maybe certain devices

require special feed stocks.

5. Conclusion : Nanotechnology, and in particular, nanoelectronics, is a topic of great importance and

urgency these days. The current CMOS transistor architecture is expected to reach its

limit some time around 2020. When that day comes, nanoelectronic technologies must be

ready for prime time. The extensive research and development projects currently under

way around the world will play a critical role in ensuring that goal is realized. While any

discoveries may not translate into commercially viable devices just yet, they do serve to

advance the study of nanoelectronics and the possible features it may enable in next-

generation electronic devices. Whatever today’s researchers develop will undoubtedly

end up benefitting the chip industry in ways that can not yet even be imagined.

7

REFERENCES

Websites

[1] http://www.physics.mcgill.ca/~peter/nanoelectronics.htm

[2] https://en.wikipedia.org/wiki/Nanoelectronics

[3] http://sciencelearn.org.nz/Contexts/Nanoscience/Science-Ideas-and-

Concepts/Nanometres-and-nanoscale

[4]https://web.stanford.edu/dept/EHS/prod/researchlab/IH/nano/what_are_nanomaterials.

html

[5]http://www.academia.edu/3009749/A_Simulation_Study_of_Silicon_Nanowire_Field

_Effect_Transistors_FETs_

[6]http://www.researchgate.net/publication/3075181_Planar_bulk_MOSFETs_versus_Fi

nFETs_an_analogRF_perspective

[7] https://en.wikipedia.org/wiki/Nano-RAM

[8] http://www.nanowerk.com/nanotechnology-in-displays.php

[9] https://books.google.com

[10] http://thefutureofthings.com/3474-nanoradio-smallest-radio-receiver-in-the-world/

[11] https://en.wikipedia.org/wiki/Energy_applications_of_nanotechnology

[12] http://www.mdlab.com/

Books

[13] Introduction to the Physics of Nanoelectronics , published in September 19,2012

by ( Mansoor B. A Jalil) .

[14] Nanoelctronic device applications HandBook , published in october 25,2011

by ( James E.Mores ) .