APPLICATION OF THIN FILMS

ANEETTA DAVISMSc NS & T, 2nd SEMMOUNT CARMEL COLLEGE

GUIDED BY: PRADEEP SIR

WHAT IS THIN FILM?

• thin = less than about one micron ( 10,000 Angstroms, 1000 nm)

• film = layer of material on a substrate

The need for thin films is because we can alter their properties and for miniature devices.

APPLICATIONS

• SOLAR CELLS• THIN FILM TRANSISTORS• OPTICAL COATING• THIN FILM BATTERIES

SOLAR CELLS• This is a cheaper raw material than crystalline silicon. No

structural damage!

• The conversion of solar light to electric power is one of the available renewable sources of energies.

• The basic physical principle involved is the absorption of photon resulting in the creation of electron-hole pairs; the excess electrons in the conduction band, and holes in the valence band.

There are several conditions that a thin film solar cell must satisfy in order to exhibit efficient photovoltaic energy conversion:

• The optical absorption coefficient (α) must be large enough

• The photogenerated electrons and holes must be collected efficiently by contacting electrodes on the both sides of the active film material

THIN FILM TRANSISTORS

• TFT is made by depositing thin films on semiconductor.

• A common substrate is glass since the primary application of TFT’s are Liquid Crystal Displays.

What is TFT LCD ?

• TFT LCD is a sandwich like structure with crystal filled between two glass plates.

• It is common in notebook computers , that it has transistor for each pixel.

How do they work ?

• TFT glass has as many TFTs as the number of pixels displayed.

• Millions of pixels create an image on the display.• TFT’s act as switches to individually turn ‘on’ and ‘off’

for each pixel• A color filter glass has color filter which generates color.• Diffuser distributing the light evenly near the viewing

area.• Liquid Glass Crystals move according to the change in

voltage between the TFT glass and color filter.

ADVANTAGES

• Light weight• Portable • Low power

consumption• High resolution• Wide variety of

commercial application

DISADVANTGES

• The general comment from the people is that the LCD TFT gets switched off after sometime .

• The liquid crystals inside the display are poisonous

• Spills off from a cracked display should be washed with soap water.

OPTICAL COATING

An optical coating is one or more thin layers of material deposited on an optical component such as a lens or mirror, which alters the way in which the optic reflects and transmits light.

ANTIREFELCTION COATING

• Whenever light travels between two interfaces of different refractive index, some of the light is reflected.

• These reflections form flare images.• The coating of optical surfaces with antireflection

coatings has resolved this problem.• The antireflection coatings should be applied to

optical surfaces containing germanium, silicon or materials with high refractive index.

Antireflection coating

THIN FILM BATTERIES

• Unlike typical batteries, thin film batteries are all solid-state.

• In many cases they can be made flexible. • They can be manufactured using normal thin film

deposition techniques. • Potential applications include:PacemakersNeural stimulatorsDrug delivery system

OTHER APPLICATIONS

• Semiconductors• Super capacitors• Data storage• Photo electrochemical cells• Drug delivery• Nanomedicine

REFERENCES

• http://www.worldscientific.com/doi/pdf/10.1142/S2010194513010696

• http://shodhganga.inflibnet.ac.in/bitstream/10603/4025/8/08_chapter%202.pdf

THANK YOU