Towards atomistic simulation of the electro-thermal properties of Nanotechnology and its transistors.

1. Towar
ds
atomi
stic
simula
tion
of
the
electr
o-
therm
al
prope
rties
of
nanow
ire
transi
tors

2. OUTLINE
Index
Nanotechnology
History of Nanotechnology
Uses of Nanotechnology
Nanotechnology in electronics
Nanotechnology for future electronics
Why only Nanotechnology for future electronics
why use Nanotechnology in computer
Nanotechnology in mobile

3. Nanotechnology
We define our Nanotechnology as :
 Nanotechnology refers to the constructing and
engineering of the functional systems at very
micro level or we can say at atomic level
 Controlling or manipulating matter on an
atomic scale.
 This is the design, characteristics, production
and application of structures, devices and
systems by controlling shape and size at
nanometric scale

4. Nanotechnology
 Creation of useful materials and using
structures, devices and systems that have novel
phenomena and other properties just like
physical , chemical, biological and functions
because of their small and/or intermediate size
 A Nanometer is one billionth of a meter,
roughly the width of three or four atoms.
The average human hair is about 25000
nanometers wide

5. Nanotechnology

6. History of Nanotechnology
• Physicist Richard Feynman
who was gave a radical lecture
at an American physical
Society meeting in 1959
He suggested that it should
be possible to make machines
at a nano-scale that “arrange
the atoms the way we want”
and do chemical synthesis by
mechanical manipulation
This invention of this idea
make him famous because this
was the birth of the study of
Nanotechnology
Richard Feynman
Plenty of Room at the
Bottom
There is nothing that I can
see in the physical law
that says the computer
elements cannot be made
enomously smaller than
they are now…

7. History of Na otechnology
In 1974 Professor Norio
Taniguchi coined the term
nanotechnology , while
working on the development
of ultra-precision machines
In 1989 Don Eigler and
Erhard Schweizer at IBM’s
Almaden Research Center
manipulated 35 individual
xenon atoms to spell out the
IBM logo
In 2004,The material was later
rediscovered , isolated and
characterized in 2004 by Andre
Geim and Konstantin
Novoselov at the University of
Manchester.This work won the
Nobel Prize in Physich in 2010
In 1981 Gerd Binning and
Heinrich Rohrer developed
the scanning tunneling
,microscope (STM),that
modern nanotechnology
began
1990 to 2000 century ,Research
groups and commitees formed to
drive nano-related research .
Consumer products making use of
nanotechnology in the Marketplace

8. History of Nanotechnology
In 2016 Jean-Pierre Sauvage, J. Fraser Stoddart
and Bernard Feringa win the Nobel Prize in
Chemistry for their research in developing Nano-
scale machines including a nanocar

9. Uses of Nanotechnology
• There are different fields those are depend on
Nanotechnology such as :
• Electronics
• Health and Medicine
• Computer
• Mobile Phone
• Transportation
• Space Exploration
• Other application

10. Nanotechnology in Electronics
 Electronics :
 For using Nano Transistor
 Nano Diode
 Organic Light Emitting Diode

11. Nanotechnology in Electronics
Improve display screen on electronics
devices
Increase the density of memory chips
Reduce the size of transistors
Today microelectronics are used and they
solve our most of the problems

12. Nanotechnology For Future Electronics
• In the future ,it is likely that become a dominant material in
flexible electronics
• Graphene is nothing but an allotrope of carbon that has superb
electrical conductivity , flexibility , and physical strength
• The two exceptional disadvantages of micro electronics are :
Physical Size
Increasing cost of fabrication integrated circuits
• To overcome these disadvantages nanotechnology can be used

13. Nanotechnology in Medicine
Medicine
Surgery
Medical
Robotics
Diagnost
-ics
Knowledge
about
Human
Body

14. Nanotechnology In Computer
Silicon Transistors are
replaced by transistors
based on carbon nano-
tubes
Size of the
microprocessors are
reduced to greater
extend
Memoristor material as
a future replacement of
flash memory

15. Nanotechnology in Modern use of Mobile
Morph a nanotechnology concept device
developed by Nokia Research Centre
The Morph will be able to charge itself from
available photovoltaic nanowire grass covering
it’s surface
It will be super hydrophobic making it extremely
dirt repllent

17. Independent University, Bangladesh
Md Morshedul Alam Murad
Computer Science & Engineering

18. Index
 Atomistic Simulation of Quantum Transport
 NEGF Simulation
 Nanowire
 Ballistic Transport
 Ballistic Transport with Phonon Scatterring
 Electron Transport

OUTLINE

19. Atomistic Quantum Transport Simulation
• Our Quantum Transport Simulations are
based on self-consistent solution of Poisson's
equation and non-equilibrium Green's
function (NEGF) approach. We developed two
methods based on either fully-3D or coupled
mode space approach self-consistent
methodology to solve electron transport
equations.

20. NEGF Simulation
Quantum transport simulation depend on NEGF
Green’s Function :
G=(E - H - ∑RB - ∑RS) Here,
H= Hamiltonia
∑=Self Energy

21. Nano-wire
 Nano-wire : Nano came from the Greek word
“dwarf” mean “billionth”
 A nanometer(nm) is a billionth of a meter
 Wire-like structure with diameter or lateral
dimension of nanometer(10-9m)
Benefits of Nano-wire :
 Various material systems can be used to fabricate
nanowires
• e.g.) Silver, Gold, Copper, …, etc. (metal)
• Si, Ge, GaAs, GaN, …, etc. (semiconductor)
• Nanowires can be assembled in a rational and
predictable because :
• Nanowires can be precisely controlled during
synthesis,
• Chemical Composition,
• Diameter,
• Length,
• Doping/electronic properties
~10-9m=1nm
~Size of DNA

22. Nano-Wire
• Different types of Nano-wires are :
Semiconductor Nano-wire as like
-Silicon Nano-wires
Oxide Nano-wires
Multi-segment nanowires
Semiconductor Quantum wire

23. NANO-WIRE
• Reliable methods exist for their parallel
assembly.
• It is possible to combine distinct Nano-
wire building blocks in ways not possible
in conventional electronics.

24. Ballistic Transport
• Ballistic transport as a result of much
reduced electron-phonon scattering,
low temperature mobility in Quantum
Wire (in-plane direction ) reaches a
rather absurd value ˜10^7cm^2/s-V ,
with corresponding mean free path
over 100
D = D = 3
nm

25. Ballistic Transport with Phonon Scatterring
e-ph scattering still matters in Lg<10nm Si FETs

26. Electron Transport

27. P-N Junction Diode
• Diode : A diode is simply a p-n junction.
The diode is a two terminal semiconductor
device that allows current to flow in only one
direction.
It is constructed of a P and an N junction
connected together.

28. Diode Operation
When the diode is “on”, it acts as a short circuit and
passes all current. When it is “off”, it behaves like
an open circuit and passes no current
No current flows because the holes and
electrons are moving in the wrong
direction
If you flip the battery around, the electrons are
repelled by the negative terminal and the holes are
repelled by the positive terminal allowing current
to flow

29. Diode Operation
• Three operation regions as like :
1) P-N junction in Equilibrium
2) P-N junction in Under Reverse Bias
3) P-N junction in Forward Bias
Under forward bias, it needs a small voltage to conduct. This
voltage drop is maintained during conduction.
The maximum forward current is limited by heat-dissipation
ability of the diode.
Usually it is around 1000 mA.
There is a small reverse bias current.

30. Doping Concentration
• The process of impurity addition is called doping
• The Semiconductor in which impurity are added is
called extrinsic semiconductor
• The electron or hole concentration can be greatly
increased by adding controlled amounts of certain
impurities
• For silicon , it is desirable to use impurities from
the group three and five
• N-type Semiconductor can be created by adding
phosphorus or arsenic
• P-type Semiconductor can be created by adding
Boron and Gallium

31. Diode Characteristics , I vs V
• When forward-biased, the diode ideally acts as a
closed (on) switch.
A small voltage is required to get the diode current
flowing . External Battery makes the Anode more
positive than the Cathode
For a silicon diode this voltage is approximately 0.7V
For a germanium diode, this voltage is approximately
0.3V
• When reverse-biased, it acts as an open (off) switch
• External Battery makes the Cathode more positive
than the Anode

32. Depletion Zone
Barrier due to depletion region very small large current can flow
Forward biased diode :
Reverse biased diode :
Very large depletion
zone
Barrier due to depletion region very large small leakage current

33. Diode Characteristic Curve

34. Diode Characteristic Curve
• The “arrowhead” in the diode symbol points in the direction
opposite the electron flow
– The anode (A) is the p region
– The cathode (K) is the n region

35. Use of Semiconductor

36. Use of Diode
• One of the major use of Diode is
Rectification
• Used as logic memory storage device
• For biasing we use diode
• Semiconductor

37. Transistor
• A transistor is a device with three separate
layers of semiconductor material (silicon,
germanium) stacked together
-The layers are made of n-type or p-type
material in the order p-n-p or n-p-n
-A terminal is attached to each layer
E= Emitter
B= Base
C = Collector

38. Naming of Transistor Terminals
• Transistor has three section of doped
semiconductor , the section of one side is called
“Emitter” and the opposite side is called
“Collector also and the middle side is called
“Base”

39. Nano-wire Transistor
Gate-all-around Transistor

40. Hole Band structure Model
GOOD :
 bulk CB and VB fitted
 extension to nanostructures
 atomistic description
 BAD :
 high computational effort
 empirical perametrization

41. Band Diagram of Silicon
Silicon Electron Band structure :

42. Gate-all-around Transistor
 The gate material surrounds the channel region
an all sides
 Gate-all-around FETs have two or four effective
gates
 Gate all around FETs have been successfully
built around a silicon nano-wire and exeed in
GaAs nano-wires