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Semiconductor Physics
Special Topics in
Nanoelectronics
Anurag Srivastava
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
Understanding Nanoelectronics
Basic Quantum Phenomena
Nanoelectronic Materials (1D, 2D and 0D)
Carbon Allotropes
Nanoscale Transport
Applications-1
–Active Electronic Devices: FETs, TFETs, SET etc
–Novel interconnects and passives
Applications-2
–Energy conversion: and storage: photovoltaics,
Other natural energy sources
–Energy conversion: and storage: thermoelectrics,
battery
Syllabus
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
List for course projects in special topics in
nano electronics
1. To study the Graphene based field effect transistor and derive the V-I curve using
NanoTCAD.
2. To study multiscale simulation of silicon nanowire transistor using NanoTCAD.
3. To study 2D nanoribbon FET using NanoTCAD.
4. To study transition metal dichalcogenide based FET using NanoTCAD.
5. To study carbon nano tube as channel material for FET and use its application for
sensing using ATK VNL.
6. To study CNTFET model and implement a digital logic circuit using model file on
SPICE.
7. To study Magnetic tunnel junction device characteristics with variable electrode
and insulating materials, mapping the characteristics to circuit level application using
ATK VNL.
8. To study single electron transistor charging energies and conductance analysis
using ATK VNL.
9. To study acene series molecular single electron transistor using ATK VNL.
10. To study semiconducting island single electron transistor using ATK VNL.
11. To study the characteristics of 2D nano sheet using two probe model using ATK
VNL.
12. To study toxic gas sensor using III-V nanowire using ATK VNL.
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
Semiconductor Physics
Is Nanoelectronics the
Future?
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
Nano World
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
1984
2014
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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.
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
Nanoscale?
1.27 × 107 m
ww
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thw
ork
s.c
om
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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s.u
cr.
edu
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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.
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
Nano- and Micro-domains
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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
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O OO O OO OO
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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
ow
orl
d1,000 nm =
Infr
ared
Ult
ravi
ole
tM
icro
wav
eS
oft
x-r
ay
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
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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.
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
Nanoscience and Nanotechnology are truly
interdisciplinary, where physicists,
chemists, engineers, biologists, computer
scientists, environmentalists, industrialists,
and policy makers have to work together.
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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)
Semiconductor Physics
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.
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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.
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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.
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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?
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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!
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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).
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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.
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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 – tunneling current
Magnetic properties – superparamagneticeffect
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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.
ABV- IIITM-Gwalior (MP) IndiaSpecial Topics in Nanoelectronics
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