BSI Nanotechnology Standards Presentation on Nanotechnology standards development
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Transcript of Nanotechnology
Nanotechnology and the Development of Computer Circuits
In this presentation…… Concept and History of
Nanotechnology Why Nanotechnology? Applications of Nanotechnology
Applications to Computer Circuits Benefits and Disadvantages of
Nanotechnology Connections with Computer
Programming
What is Nanotechnology?
Nanotechnology is the creation and use of materials or devices at extremely small scales.
1 nm = 0.000000001 m
Nanotechnology Foretold Concept first introduced by
American physicist Richard P. Feynman (1918-1988)
Calculated that an encyclopedia set could be compressed to fit the head of a pin.
Predicted several aspects in today’s nanotechnology
Advanced microscopes Developments in fabrication
methods Possibilities of atom-to-atom
assembly
Tools In Nanotechnology
The main tools used in nanotechnology are three main microscopes Transmission Electron Microscope
(TEM) Atomic Force Microscope (AFM) Scanning Tunneling Microscope (STM)
Transmission Electron Microscope (TEM) Uses high-energy
electron beam to probe material with thickness < 100 nm.
Some electrons are absorbed or bounced off object; some pass through the object and make magnified images
Digital camera records images.
Atomic Force Microscope (AFM)
Use small silicon tip as probe to make images of sample material
Probe moves along surface
Electrons of atoms in sample repel those in probe
Creates 3-D images
Scanning Tunneling Microscope (STM) Uses nanosized probe
to scan objects and materials
Uses tunneling to detect surface and creates a map of surface
Rate of electrons that tunnel from probe to surface related to distance between probe and surface
Other Uses for Tools Microscopes used for
imaging and manipulating nanostructures
“Arms” in AFMs and STMs used to move around individual atoms
Scientists at IBM made this image using an STM to with iron atoms into a circular structure
A Study and Analysis of Blue Morpho Butterfly Wing Nanostructures for Commercial Fabrication
Abstract
This study focuses on the photonic crystals found in the scales of a butterfly wing, particularly those of the species known as the blue Morpho Rhetenor butterfly. To study these nanostructures, scanning electron microscope (SEM) imaging and the development of a finite-difference time-domain (FDTD) program were necessary. The FDTD program produced a graphical display of what colors are reflected as a result of light propagation. The purpose of this study was to find what method of fabrication is necessary to possibly reproducing these photonic crystals. Such fabrication methods would eventually be applied for commercial uses.
What Are Photonic Crystals?
• Periodic dielectric nanostructures affecting propagation of EM waves; allows and forbids certain electron energy bands.• Give rise to such optical events as the inhibition of spontaneous emission and low-loss waveguiding when allowed propagating electromagnetic waves are not present. • The basic phenomenon behind photonic crystals is based on diffraction, or the bending and spreading of waves.• Periodicity of photonic crystal structures must be at the same length scale of the wavelength of the EM waves; allows them to operate in the visible portion of the spectrum.• Bragg’s Law: λB = 2neffΛ
Photonic Crystals Found In Nature• Opal • Sea Mouse • Butterfly• Peacock
Applications
Researchers intend to developed adequate fabrication methods for commercial uses:
• Cosmetics
• Clothing
• Encoding in Fiber Optics
• Inhibition of Spontaneous Emission
The Blue Morpho Rhenetor Butterfly
• Paints
• Fabrics
• Integrated Optics Components
• Computer Circuits*
The Blue Morpho Rhenetor Butterfly is the focus of our project as we study the
photonic crystals found on the scales of the wings.
Finite-Difference Time-Domain (FDTD) Program
Recorder Layer
Bottom PML
Top PML
Source Field
Nanostructure
FDTD ModelTop PML
FDTD Model
A finite-difference time-domain (FDTD) program was developed in MATLAB to simulate the photonic behavior of the nanostructures directly from the captured SEM images. This program simulates the natural phenomenon that takes place when visible light is incident on the nanostructures within the scales of the wings.
FLOWCHART
The white light enters the source layer.
The white light scatters randomly across the
nanostructure.
PML absorbs light.
The nanostructure behaves as a
wavelength-dependent mirror.
The recorder layer detects which colors are reflected.
Data is displayed in a curve plot.
The FDTD modeling program uses Maxwell’s curl equations for source-free materials:
HE
t
E
Ht
(1) and (2).
0
EE
0
1 HE
c t
2
0
n EH
c t
If , then (3) and (4).
0
1y xzE HE
y z c t
0
1 yx zHE E
z x c t
0
1y x zE E H
x y c t
2
0
y xzH EH n
y z c t
2
0
yx zEH H n
z x c t
2
0
y x zH H En
x y c t
Vectors E and H are then, written in their vector components.
(5) (6) (7)
(8) (9) (10)
RHDx xxE t t E tE
t t
2 2
CDy y
z zzH y H yH
y y
The derivatives in can be approximated as:
and .
These derivatives are plugged into each of the E and H vectors components to create update equations. For (8),
2 202
y yz zx x
H y H yE t t E t c
t n y
2 202
y yz z
x x
H y H yc tE t t E
n y
(11).
The FDTD algorithm works by continuously forcing Maxwell’s curl equations over the duration of the model.
Numerical Results
Computer Circuits Computer circuits are
small pieces of semiconducting material containing an electronic circuit.
Most commonly used in computers
Consists of as many as millions of transistors. Nanotechnology is
applied to the reduction in the size of
these computer circuits!!!
Methods of Developing Computer Circuits
The most common method of fabricating computer circuits is the top-down method Thin films of materials, which make
up a mask, are deposited on a silicon wafer
Unnecessary portions are etched off
Benefits of Nanotechnology
In the computer world, nanotechnology is important to the development of small computer circuits that can reduced the size of computers.
Disadvantages of Nanotechnology
Safety hazards with nanomaterials Some studies detected possible
cancer-causing properties of carbon nanotubes
Some nanomaterials bounded with other materials or components
Effects on Society
Connections with Computer Science
With the continual advancements and applications of nanotechnology to computer science, computers will surely improve drastically in the functionality, speed, and overall performance, as well as decrease in size providing more breathing room at home, at the office, or at school. These advancements have also begun to pave the way for portable devices such as MP3 players and PDAs. The world of computer science can only grow exponentially through the assistance of nanotechnologists. This topic interest me because I intend to focus my career in the research and development of nanodevices that affect the medical and computer science fields, as well as the everyday world in which we live.
Where Can We Learn More???
Most lower-level computer science courses at Spelman (and Morehouse) may touch up on nanotechnology, or at least speak of their overall contributions without actually using the term itself.
Bibliography