photodiode

Photodiode

Sahil Bansal

Sahil Chhabra

•A photodiode is a type of photo detector

capable of converting light into either current

or voltage

•It converts light energy into electrical energy.

•Photodiodes are similar to regular

semiconductor diodes except that they may

be either exposed with a window or optical

fibre to allow light to reach sensitive part of

device

Material commonly used for

producing photodiode

includes:

Working of Photodiode

Photodiodes are of two types PN and PIN.

At PN junction there will be concentration gradient that causes electrons to diffuse into p-type region and holes into n-type region. This diffusion results in an opposing electric potential, often referred to as an Depletion region.

Any photon absorbed in the depletion region causes moment of charge carriers

This moment of charge carriers across the junction

upsets the electrical balance and produces a

photocurrent, which can be detected at

electrodes.

Applications

In electronic devices

In smoke detectors• Light sensors

• Used to measurer light intensity in

science and industry

LED are semiconductor p-n junctions that under forward bias conditions can emit

radiation by electroluminescence in the UV, visible or infrared regions of the

electromagnetic spectrum. The qaunta of light energy released is approximately

proportional to the band gap of the semiconductor.

What is LED?

Applications of LEDs

Your fancy telephone, i-pod, palm pilot

and digital camera

Getting to know LED

Advantages of Light Emitting Diodes (LEDs)Longevity:The light emitting element in a diode is a small conductor chip rather than a filament which greatly extends the diode’s life in comparison to an incandescent bulb (10 000 hours life time compared to ~1000 hours for incandescence light bulb)Efficiency:Diodes emit almost no heat and run at very low ampere.

How does it work?

P-n junction Electrical Contacts

A typical LED needs a p-n junction

Junction is biased to produce even more

e-h and to inject electrons from n to p for

recombination to happen

There are a lot of electrons and holes at

the junction due to excitations

Electrons from n need to be injected to p

to promote recombination

Recombination

produces light!!

Thank you