Nano Materials & Nano Fabrication

1. Nanomaterials & Nanofabrication

2. Introduction

3. What is nanomaterial?
Nano-scale
⮚ A material with any external dimension in the nanoscale (1-100 nm) or having internal
structure or surface structure in nanoscale.
⮚ As a result of their unique size, the physical and chemical properties of nanomaterials differ
from those of their larger-scale.
Introduction

4. Nanotechnology
Refers to the fabrication and application of entities whose feature sizes range from less than 1 nm
to 100 nm The entities include films, coatings, dots, lines, wires, tubes, structures, and systems.
Nanoscience
Nanoscience is the ‘study’ of the fundamental principles of nanomaterials (molecules and
structures with at least one dimension between 1 and 100 nm). This includes the physical, chemical
and biological aspects of Nano entities.
Introduction

5. Classification Of Nanomaterials
Nanomaterials are classified based on the number of dimensions, which are not confined to the
nanoscale range as follows:
Zero-dimensional (0-D)
One-dimensional (1-D) Two-dimensional (2-D)
Three-dimensional (3-D)

6. Grain size at nanoscale
Nanoparticles
Nano layer or Nano film
Bulk materials in nano-size

7. Fabrication Methods
Top-down approach Bottom-up approach
There are two approaches in nanofabrication:
⮚ start with atoms or molecules and
build up to nanostructures.
⮚ Examples: production of carbon
nanotubes and self assembly.
⮚ start with macro-size or bulk material
and then is reduced to Nano-size.
⮚ Examples: mechanical milling, sever
plastic deformation and lithography.
Bulk material nanomaterial Atoms or molecules
Top-
down
Bottom-up

8. Mechanical Milling
⮚ One of the mechanical methods to produce nanoparticles
⮚ Its also known as ball milling
Mechanical milling has many advantages:
⮚ Simple equipment
⮚ Low cost
How it works?

9. Severe Plastic Deformation
Plastic deformation Grain size refinement
Ultra fine grain size (500 nm) Nano grain size (100 nm)
SPD
Before SPD After SPD Equal channel angular pressing
(ECAP)

10. Lithography
“transferring an image from a mask to a receiving substrate”
Lithography process involves three steps:
Lithography
Photo Lithography Scanning Lithography

11. Scanning Lithography
⮚ It is performed point by point through a computer controlled program.
⮚ Examples: electron beam lithography and ion beam lithography.
⮚ Mask less process.
⮚ Higher resolution (less than 50 nm).
⮚ Slow process, not suitable for high production.
⮚ More expensive.

12. Electro-Spinning
⮚ It is a fiber production method which uses electrical force to draw charged fibers in the
order of hundred nanometers from polymer solutions or polymer melts.

13. Electro-Spinning
Working principal
When electrical field is applied the shape of the droplet (sphere) begins to change until the
voltage reach a certain value where electrical force equal surface tension. At this value Taylor
cone is formed. By increasing the voltage the electrical force overcome the surface tension and a
jet of fiber is emitted from the droplet.

14. Production of carbon nanotubes
CNTs consist of carbon atoms bonded together in the shape of a long tube.
CNTs have distinguished properties:
Electrical properties
Mechanical properties
Thermal properties

15. Production of carbon nanotubes
Laser evaporation method

16. Production of carbon nanotubes
Carbon arc technique

17. CH4
Carrier Gas
Heating
coils
Cooled
collector
CNTs
substrate
Reaction
chamber
Quartz tube
outlet
Production of carbon nanotubes
Chemical vapor deposition (CVD)

18. Self-assembly
a phenomenon where the components of a system assemble themselves to form a larger
functional unit. This assembly can be due to direct specific interaction, collective effects, and/or
occur indirectly through their environment.