Introduction to

Nanoscience and Technology

Prof. Anurag SrivastavaWeb address: http://tiiciiitm.com/profanurag

Email: profanurag@gmail.com

Visit me: Room-110, Block-E, IIITM Campus

Nano World

1984

2014

Nano:From the Greek nanos -meaning "dwarf”,

this prefix is used in the metric system to mean 10-9 or 1/1,000,000,000.

Nanoscale?

1.27 × 107 m

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0.22 m 0.7 × 10-9 m

Fullerenes C60

12,756 Km22 cm 0.7 nm

10 millions times

smaller

1 billion times

smaller

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Nano is Different: Size Matters

Bulk Gold = Yellow

Nano Gold = Red

Quantum Dots for

Imaging and Diagnostics

Optical properties change withsize. Depending on their sizeCdSe particles can appear greenor red in colour.

2 nm 5 nm

Quantum dot size can be controlled during

their synthesis

nanocrystals absorb all energies higher than

their band gap, they can also be used as color

converters. Sizes of biological molecules are

also on the order of a few nanometers.

Why Is Nanotechnology So Cool?

Bulk Gold

mp = 1064° C

Color = gold

1 nm gold particles

mp = 700 °C

lmax = 420 nm

Color = brown-yellow

20 nm gold particles

mp = ~1000 °C

lmax = 521 nm

Color = red

100 nm gold particles

mp = ~1000 °C

lmax = 575 nm

Color = purple-pink

Nano- and Micro-domains

Red blood cells(~7-8 mm)

DNA

~2-1/2 nm diameter

Things Natural

Things Man made

Fly ash~ 10-20 mm

Atoms of siliconspacing ~tenths of nm

Head of a pin1-2 mm

Quantum corral of 48 iron atoms on copper surfacepositioned one at a time with an STM tip

Corral diameter 14 nm

Human hair~ 60-120 mm wide

Ant~ 5 mm

Dust mite

200 mm

ATP synthase

~10 nm diameterNanotube electrode

Carbon nanotube~1.3 nm diameter

O O

O

OO

O OO O OO OO

O

S

O

S

O

S

O

S

O

S

O

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Fabricate and combine nanoscale building blocks to make useful devices, e.g., a photosynthetic reaction center with integral semiconductor storage.

1 cm

10 mm

Mic

row

orl

d

0.1 nm

1 nm

0.01 mm

10 nm

0.1 mm

100 nm

1 (mm)

0.01 mm

10 mm

0.1 mm

100 mm

1 mm

10-2 m

10-3 m

10-4 m

10-5 m

10-6 m

10-7 m

10-8 m

10-9 m

10-10 m

Vis

ible

Nan

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1,000,000 nm =

Zone plate x-ray “lens”Outer ring spacing ~35 nm

The Scale of Things – Nanometers and More

MicroElectroMechanical (MEMS) devices10 -100 mm wide

Red blood cellsPollen grain

Carbon buckyball

~1 nm diameter

Self-assembled,

Nature-inspired structure

Many 10s of nm

Challenges

Nanoscience is the study of phenomena and manipulations of

materials at atomic(~ 0.5 nm),

molecular (~1-5nm) and

macromolecular (~5-100 nm) scales,

where properties differ significantly from those of the bulk materials.

Nanotechnology concerns design, characterization,

production and application of structures, devices and systems by

controlling shape and size at nanometer scale.

Nanotechnology is the creation of functional materials, devices,

and systems through control of matter on the nanometer (1 to 100

nm) length scale and the exploitation of novel properties and

phenomena developed at that scale.

Source: Nanoscience and nanotechnologies: opportunities and uncertainties, The Royal Society & the

Royal Academy of Engineering, London-2004.

Nanoscience and Nanotechnology are truly

interdisciplinary, where physicists,

chemists, engineers, biologists, computer

scientists, environmentalists, industrialists,

and policy makers have to work together.

Nanoscience?

When people talk about Nanoscience, they start by describing things in their own way

Physicists and Material Scientists point to things like new nanocarbon materials:

They effuse about nanocarbon’s strength and electrical properties

GrapheneCarbon Nanotube

C60 Buckminster Fullerene

Nanotechnology is…

Not just new products — a new means of production

Manufacturing systems that make more manufacturing systems

— exponential proliferation

Vastly accelerated product improvement — cheap rapid

prototyping

Affects all industries and economic sectors — general-purpose

technology

Inexpensive raw materials, potentially negligible capital cost —

economic discontinuity

Portable, desktop-size factories — social disruption

Impacts will cross borders — global transformation

Nano-bio

Biologists counter that nanocarbon is

a recent discovery

THEY’VE been studying DNA and

RNA for much longer

(And are already using it to transform

our world)

What is Nanoelectronics?

Nanoelectronics refer to the use of nanotechnology on

electronic components, especially transistors. Although the term

nanotechnology is generally defined as utilizing technology less

than 100 nm in size, nanoelectronics often refer to transistor

devices that are so small that inter-atomic interactions and

quantum mechanical properties need to be studied extensively.

As a result, present transistors do not fall under this category,

even though these devices are manufactured with 45 nm, 32 nm,

or 22 nm technology.

Is this technology new?In one sense there is nothing new…

Whether we knew it or not, every piece of technology has involved the manipulation of atoms at some level.

Many existing technologies depend crucially on processes that take place on the nanometer scale. Ex: Photography & Catalysis

Nanotechnology, like any other branch of science, is primarily

concerned with understanding how nature works.

Why is this length scale so important?There are five reasons:

1. The wavelike properties of electrons inside matter are

influenced by variations on the nanometer scale. By patterning

matter on the nanometer length, it is possible to vary

fundamental properties of materials (for instance, melting

temperature, magnetization, charge capacity) without

changing the chemical composition.

2. The systematic organization of matter on the nanometer length

scale is a key feature of biological systems. Nanotechnology

promises to allow us to place artificial components and

assemblies inside cells, and to make new materials using the

self-assembly methods of nature.

3. Nanoscale components have very high surface areas, makingthem ideal for use in composite materials, reacting systems,drug delivery, and energy storage.

4. The finite size of material entities, as compared to themolecular scale, determine an increase of the relativeimportance of surface tension and local electromagneticeffects, making nanostructured materials harder and lessbrittle.

5. The interaction wavelength scales of various external wavephenomena become comparable to the material entity size,making materials suitable for various opto-electronicapplications.

Why is this length scale so important?

How Small We can make the

grains?

Because of high surface areas conventional

powders methods reach their limits at 10-6 m (1

micron)

Smaller particles can be made but special

methods are needed!

Working at the nanoscale Working in the nanoworld was first proposed by

Richard Feynman back in 1959.

But it's only true in the last decade.

The world of the ultra small, in practical terms, is a

distant place.

We can't see or touch it.

Because, optical microscopes can't provide images of

anything smaller than the wavelength of visible light

(ie, nothing smaller than 380 nanometres).

Some “Nano” definitions Cluster

A collection of units (atoms or reactive molecules) of up to about 50 units

Colloids A stable liquid phase containing particles in the 1-1000

nm range. A colloid particle is one such 1-1000 nm particle.

Nanoparticle A solid particle in the 1-100 nm range that could be

nonocrystalline, an aggregate of crystallites or a single crystallite

Nanocrystal A solid particle that is a single crystal in the nanometer

range

What is so special about

nanoscale Atoms and molecules are generally less than a nm.

Size-dependent properties

Surface to volume ratio

A 3 nm iron particle has 50% atoms on the surface

A 10 nm particle 20% on the surface

A 30 nm particle only 5% on the surface

Not just size reduction but phenomena intrinsic to nanoscale

Size confinement

Dominance of interfacial phenomena

Quantum mechanics

New behavior at nanoscale is not necessarily predictable from what we know at macroscales

ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics

Nanostructures

Sun, Y.; Xia, Y. Science

2002, 298, 2176.

Courtesy of Liza Babayon

Baughman, R. H.; Zakhidov, A. A.;

de Heer, W. A. Science 2002, 297, 787

Vigolo, B; Penicuad, A.; Coulon, C.; Sauder, C.;

Pailler, R Journey, C.; Bernier, P. Poulin, P.

Science 2000, 290, 1331

CdSe Quantum Dots

Carbon NanotubesNoble Metal Nanoparticles

Courtesy of the

Van Duyne group

Size Matters As the size of an object becomes smaller

and smaller, approaching nanoscale, the

surface molecules become increasingly

important relative to internal molecules

Because of the increasing proportion of surface

molecules relative to internal molecules

Thus, the surface properties of materials of

nanoscale objects become more influential in

determining the behavior of the objects

And the influence of bulk properties is reduced

Properties vary with the size of

the material

(Bulk) Gold is a shiny yellow metal

Nanoscopic gold, i.e. clusters of gold atoms

measuring 1 nm across, appears red

Bulk gold does not exhibit catalytic properties

Au nanocrystal is an excellent low temperature

catalyst.

Therefore, if we can control the processes

that make a nanoscopic material, then we can

control the material’s properties.

Size Dependent Properties

Chemical properties – reactivity, catalysis

Thermal properties – melting temperature

Mechanical properties – adhesion, capillary forces

Optical properties – absorption and scattering

of light

Electrical properties – tunnelling current

Magnetic properties – superparamagneticeffect

Some Size Effects: Atomic

Bonding

Two types of atomic bonds:1. Primary bonds –combining atoms into molecules

2. Secondary bonds – attraction between molecules to form bulk materials

Secondary bonds become more important for nanoscale objects because their shapes and properties depend on these secondary bonding forces Thus, material properties and behavior of nanoscale

objects are different from those of much larger objects

Size Effects: Quantum

MechanicsBranch of physics concerned with the notion that all forms of

energy occur in discrete units when observed on a smallenough scale

Example: electricity is conducted in units of electrons

Quantum mechanics are significant for nanoscale entities

One implication: As microelectronic devices reachnanoscale, we approach the limits of technologicalfeasibility of current fabrication processes for integratedcircuits

Properties of nanostructured materials are size dependant.Properties can be tuned simply by adjusting the size, shapeor extent of agglomeration.

Unique Properties of

Nanoscale Materials

Quantum size effects result in unique mechanical, electronic,

photonic, and magnetic properties of nanoscale materials

Chemical reactivity of nanoscale materials greatly different from

more macroscopic form, e.g., gold

Vastly increased surface area per unit mass, e.g., upwards of

1000 m2 per gram

New chemical forms of common chemical elements, e.g.,

fullerenes, nanotubes of carbon, titanium oxide, zinc oxide, other

layered compounds