PHOTODIODE

Photodiode

• This is a type of light sensor that changes the energy from light into electricity (voltage or current).
• A photodiode is a type of device that is not fully conducting and has a PN junction.
• One more layer, called the intrinsic layer, lies between the p (positive) and n (negative) layers. In order to make electricity, the photodiode needs light energy.
• You may also hear it called a photodetector, a photosensor, or a light detector.
• The p-side of the photodiode is connected to the negative terminal of the battery (or the power source), and the n-side is connected to the positive terminal of the battery. This is called reverse bias.
• Silicon, Germanium, Indium Gallium Arsenide Phosphide, and Indium Gallium Arsenide are common materials used to make photodiodes.
• A photodiode has optical filters, a lens, and a surface area on the inside.
• The reaction time goes down as the surface area of the photodiode grows. There aren't many photodiodes that look like LEDs. As you can see below, it has two ends.
• The shorter end is the cathode and the longer end is the anode.
• In science, the following symbol can be used to show a photodiode:

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• An LED and a photodiode both have the same sign, but the arrows on the photodiode point inward, which means it collects light energy while the LED gives off light energy.

Working of Photodiode

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• When light with more energy than the semiconductor's band gap hits the photodiode, electron-hole pairs are created near the depletion region of the p-n junction diode.
• The electric field of the depletion area keeps these electrons and holes apart, so they don't join back together.
• Atoms move toward the semiconductor's n side, while holes move toward its p side. An emf is seen because of this movement.
• If you connect an external load to a photodiode, you can see the current moving through the load.

Different Uses of Photodiode

• Photodiodes are used for many easy tasks in everyday life.
• The reason they are used is that photodiodes respond linearly to light. A lot of current flows through the sensor when a lot of light hits it.
• A galvanometer that is attached to the circuit will show the rise in power.
• With the help of optocouplers, photodiodes help to separate the electric current. Optocouplers connect two separate circuits optically when light shines on them alone.
• Electrically, though, the connections will be cut off. When compared to other devices, optocouplers work quickly.
• Safety gadgets, such as smoke and fire alarms, also use photodiodes. It's also used on TV stands.
• They work as picture sensors when used in cameras. As well as photomultiplier tubes and scintillators, it is used in charge-coupled devices and batteries.
• Photodiodes are also used in a lot of medical situations, such as in devices that study data, detectors for computed tomography, and blood gas monitors.

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