Thin film presentation

1. THIN FILMS
Presented by
KOUSHIK DEKA
B Ed 1st Sem
Roll no. 16
Namrup College of Teachers Education

2. A thin film is a layer of material varies from fractions of a nanometer
(monolayer) to several micrometers in thickness
Examples: household mirror, soap bubble, oil film, CD etc.
Fig : soap bubble Fig : Thin oil film

3. Thin Film Interference :
A clear and colorless substance can appear to give an array of colors when it is
found in a very thin film
Fig : Thin film interference in soap bubble
Fig : wings of butterfly acting as thin film
Fig : light incident on oil film on water

4. “A thin film interference results in different array of
colors.”
This is due to interference of light waves reflected from
top and bottom surfaces.
Since each color has different wavelength , different
angle of incidence and different thickness of thin film
layer. It creates a rainbow like effect

5. Classification of thin films :
Based on structure:
 Amorphous
 Single crystal
 Polycrystalline
Based on thickness:
• Thicker films ( > 1000 Å)
• Thin films (100-1000 Å)
• Ultra thin films (50-100 Å)

6. Properties of thin films
Thin films may be
• Not fully dense
• Two-dimensional (very thin)
• High surface to volume ratio
• Very compact
• Highly dependent on thickness
• Different from bulk materials

7. Difference between bulk and thin
films
Bulk materials have constant physical
properties , regardless of size,
physical and chemical properties
Bulk materials are larger in size
Chemically less reactive
Thin films have higher physical , optical
, chemical properties. And they depend
on roughness thickness
Thin films are made up of nano-size
Chemically more reactive
Major properties like thermal, optical properties ,conductivity etc. get
enhanced when bulk covert in form of thin films
Example : gold

8. Thin film deposition:
The act of creating and applying a thin film to a surface is called thin film
deposition. Deposition techniques are mainly classified into 2 categories
physical and chemical.
(i) Physical vapor deposition:
a) vacuum evaporation
b) sputtering
(ii) Chemical vapor deposition

9. Applications:
(1) Optical coating:
This optical coating reduces reflection of optical surfaces.
Example : anti reflection coating on sun glasses
(2)Decorating coating:
The oldest application of thin films is decorating coating. Thin
gold leaves were used in India 5000 years ago.
(3) Corrosion prevention:
Thin films are used as anti-corrosion protection in jewellery,
wrist watches etc.

10. (4) Thin film solar cells :
It enhances photothermal conversion efficiency. Because these thin film
materials are able to convert solar energy into electric. And they reduces cost
of solar cells
(5) Thin film batteries:
Thin film printing technology is used to applying Lithium polymers to different
substances to create special kind of batteries
(6) Electrical devices:
Due to high conductivity , thin layers of metals and alloy are used in electrical
devices . Integrated circuits and semiconductor devices are made from stacks of
thin films of conductors semi conductors