OPTOELCTRONIC DIODES

• Using semiconductors, optoelectronics studies, designs, and makes gear that changes electrical energy into light and light into energy. It's what links vision and circuits together.
• Some semiconductors can change light energy into electrical energy or electrical energy into light energy. These are called optoelectronic devices. 
• The thing that this is made of is solid crystalline crystals, which are heavier than insulators but lighter than metals.
• An optoelectronic device is a piece of electronics that works with light. This technology is used in many optoelectronic uses, such as in the military, telecommunications, medical equipment, and automatic entry control systems.

Properties of Optoelectronic Devices

• These devices have a longer range.
• They are cheap.
• They are the size of a manometer.
• They use strong light sources.
• It is the p-n junction devices that make the carriers, and photons are what make them work.
• Light-emitting diodes (LEDs), Solar cells, and Photodiodes are all types of optical devices. Let's talk about these gadgets in more depth.

Light Emitting Diode (LED)

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• An LED is a p-n junction diode that has been highly doped and is used in forward bias.
• We already know that the n side has a lot of electrons and the p side has a lot of holes.
• When electricity is put into a diode with forward bias, electrons move from the n side to the p side, which has holes.
• The release of a photon, which is the light we see in LEDs, happens when one electron and one hole come together.

Working of an LED

Properties of an LED

• The amount of light an LED gives off is directly related to the amount of current it has.
• This is because more current means more photons are released, which means more light.
• It depends on the semiconductor's band gap (the space between the conduction band and valence band) and what color the light it gives off is. An LED's reverse breakdown voltage is low.
• Only compound semiconductors, such as GaAs, can be used to make LEDs.

Symbol for LED

In physics, the following symbol can be used to show an LED:

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• The benefits of an LED are that it is durable and doesn't need any upkeep, it responds quickly, it gives off only one color of light, it needs low energy to work, and it uses less power.

Solar Cell

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• A solar cell is a piece of technology that turns light energy into electricity. This is a p-n junction semiconductor, and it only makes electricity when light hits it with more energy than its band gap.

Working of a Solar Cell

• When photons of light with more energy than the semiconductor's bandgap are thrown into the solar cell, the photons' energy is passed to the cell.
• It is the photons' energy that is transferred to the electrons in the lower, p-type layer.
• These electrons can then jump to the upper, n-type layer and move into the circuit through the metal conducting strips. It is this movement of the electrons that creates the current in the circuit.

Photodiode

• It's a machine that turns light energy into electricity. In reverse bias situations, it's used, and it's usually made of materials like Indium gallium arsenide, Silicon, and Germanium.

Photodiode symbol

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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

• When light with more energy than the semiconductor's band gap hits the photodiode, pairs of electrons and holes are created near the depletion region of the p-n junction diode.
• The electric field of the depletion region keeps these pairs of electrons and holes apart so that they cannot recombine.
• Because the electrons move toward the n side and the holes move toward the p side of the semiconductor, an emf is seen.
• If you connect an external load to a photodiode, you can see the current moving through the load.

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