What is LED and how does it work?

Do you know what is LED? What have you used it for? Do you know how this works? If you know the answers to these questions, then it is a very good thing and if not, then there is nothing to worry at all. Because today we are going to get complete information about this in this article.

LED or it is also called a Light-emitting diode. It is a semiconductor device that emits light when current or electricity passes through it. Here the light is produced only when the particles (which are electrons and holes) inside combine with each other in this semiconductor material.

Since here the light is generated from solid semiconductor material only, hence it is also called a solid-state device. LED has been a very important invention of this era because today it is being used by a large number of people.

So, today I thought that why should not you be given complete information about what is LED so that you people also know about this new invention. So without delay let's start and know what is LED and how it works.

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What is LED

The full form of this LED is Light Emitting Diode. This is a very latest invention and it is being used the most today. These magic light bulbs are used in a very wide range of applications from your cell phone to large advertising display boards.

You can see it anywhere. Today its popularity and applications are increasing day by day because it has such excellent properties. LEDs, in particular, are very small and with this they use very little power.

We can keep this LED in the category of an "active" semiconductor. We can also compare this diode with the normal general-purpose diode, but the biggest difference is that it has the ability to emit different types of light.

If both the terminals (anode and cathode) located in this LED are connected to a voltage source in its correct polarity, then it can produce light of different colors depending on the semiconductor material present in it. does.

The bright light that is produced when the LED is lit is monochromatic and is of a single wavelength. The output range of an LED is from red (at wavelength approximately 700 nanometer) to blue-violet (about 400 nanometer). Some LEDs emit infrared energy (IR) which is also called IRED (infrare-emitting diode).

An LED mainly consists of two elements of processed material which are P-type semiconductor and N-type semiconductor. These two elements are placed in direct contact and a region is formed which is also called P-N junction.

These are similar to other diodes but have a transparent package which helps visible or IR energy to pass through.

History of LEDs

LED was first brought to this world in 1907 when electroluminescence was discovered by British scientist H.J.Round in Marconi Labs.

After that, in 1961, when Gary Pittman and Robert Biard were doing their experiments in Texas Instruments, they discovered that gallium arsenide emits infrared radiation when exposed to electrical current, which they later named as infrared LED. made a patent.

After that, the first visible light LED (red) came in 1962. It was developed by Nick Holonyak Jr. By when he was working at General Electric. That's why Holonyak is also called "father of the light-emitting diode".

After that, in 1972, M. George Crawford, who used to be a student of Holonyak, first described the yellow LED and increased the light output of red and red-orange LEDs by a factor of 10, which was at that time I was quite an achievement.

Working Principle of LED

A light-emitting diode is a two-lead semiconductor light source. It is a p-n junction diode which emits light when activated. When a suitable voltage is applied to its leads, then the electrons in it recombine with the electron holes in the device.

Due to this they release energy in the form of photons. This effect is called electroluminescence and here the color of the light (which corresponds to the energy of the photon) is determined by the energy band gap of the semiconductor.

Complete Working Principle of LED

The material used in LEDs is basically aluminum-gallium-arsenide (AlGaAs). In its original state, the atoms of this material are very strongly bonded. Here, due to the absence of free electrons, it is impossible to conduct electricity.

Infrared light is produced by using Gallium Arsenide (GaAs) as a semiconductor. Red and yellow light are produced by using Gallium-Arsenide-Phosphorus (GaAsP) as a semiconductor.

Red and green light are produced by using Gallium-Phosphorus (GaP) as a semiconductor.

Infrared light is produced by using Gallium Arsenide (GaAs) as a semiconductor. Red and yellow light are produced by using Gallium-Arsenide-Phosphorus (GaAsP) as a semiconductor.

Red and green light are produced by using Gallium-Phosphorus (GaP) as a semiconductor.

LEDs Advantages

Let us now know about the Advantages of LEDs: –

• Very less voltage and current is required to light up the LED.
• Voltage range – 1 to 2 volts, Current – ​​5 to 20 milliamperes.
• Here the total power output is much less than 150 milliwatts.
• Here the response time is very short - which is only 10 nanoseconds.
• This device does not require any heating and warm-up time.
• Their size is very small and it is lightweight.
• Their construction is very rugged and hence it can tolerate shock and vibrations.
• The lifetime of LED is more than 20 years.

LEDs Disadvantages

Let us now know about the Disadvantages of LEDs: –

• If a little more voltage and current is used on it, then it can easily get damaged.
• This device has a very high and wide bandwidth in comparison to laser.
• Here temperature depends on radiant output power and wavelength.

LED types

Ever since the invention of LEDs, there has been a lot of change in its technology and its variety is also being found, in which they have different properties and applications.

1. Traditional inorganic LEDs

This type of LED is mainly the traditional form of diode which is also available since 1960s. They are manufactured using inorganic materials. The most commonly used compound semiconductors here are Aluminum gallium arsenide, Gallium arsenide phosphide, etc.

Here the color of these LEDs depends on which materials are being used.

There are many categories of these inorganic LEDs and it comes in many styles:

Single color 5 mm, etc – This is the traditional LED package.

Surface mount LEDs

Bi-colour and multicolor LEDs – In these types of LEDs, many individual LEDs are placed together and they are turned on through different voltages.

Flashing LEDs – in which a short time is integrated in their package

alphanumeric led displays

2. High Brightness LEDs

This is also a type of inorganic LED which is used for lighting applications. It is also similar to basic inorganic LED but it has greater light output.

These LEDs have to tolerate much higher current levels and power dissipation to produce higher light output. They are mounted above the heatsink so that unwanted heat can be taken out. These lights are used in place of traditional lights.

3. Organic LEDs

Organic LEDs are a slightly advanced version of the basic light-emitting diode. Organic materials are used in these LEDs as its name suggests. The organic type of LED displays is based on organic materials which are manufactured with the help of sheets and which provide a diffuse area of ​​light. Here typically a very thin organic material film is printed on a substrate made of glass.

Then a semiconductor circuit is used so that electrical charges can be brought to the imprinted pixels, which help it to glow.

Similarly, LED technology is being improved gradually so that their efficiency level can be increased and they can be used more.

Applications of LEDs

• Indicator lights:
• They are used in Indicator lights. Which is used in two-state (i.e., on/off), bar-graph, and alphabetic-numeric readouts.
• LCD panel backlighting:
• Here Specialized white LEDs are used in flat-panel computer displays.
• Fiber optic data transmission:
• It is easy to do modulation through them, which allows wide communications bandwidth, that too with minimum noise, which gives high-speed and accuracy.
• Remote control:
• It is used in "remotes" in homes.
• Optoisolator:
• They are used in Optoisolator where it is easy to connect two stages without any unwanted interaction.