Light-Emitting Diode - An Introduction, Structure, and Applications of LEDs

Introduction to LED
Structure of LED
Application of LED
Summary

Introduction to LED

A light-emitting diode or more commonly referred to as LED, is basically a semiconductor that when an electric current passes through it emits visible light. In other words, LED is basically a tiny light bulb similar to an incandescent bulb. The major difference between the two is that LED does not have a filament that will burn out and they do not get remarkably hot. The service life of LED last just as long as a standard transistor. In addition, their small plastic bulb makes LED a lot more durable.

Structure of LED

LED contains two elements of processed materials referred to as the P-type and N-type semiconductors. The way that an LED is made is that an electrode attached to the P-type semiconductor layer is coated or deposited on an N-type semiconductor substrate. Hence they are in direct contact. The region where the N-type semiconductor comes in contact with the P-type semiconductor is known as the P-N junction.

LED is similar to other forms of diodes. What separates LED from other forms of diodes is that LED has a transparent package that allows infrared or visible energies to pass through and the P-N junction area can be shaped to tailor to the application

The light generated by the LED is not particularly bright and mostly it is monochromatic. The output can range from red to blue and violet. Another form of LED known as infrared-emitting diode emits infrared energy instead.

Conventional LEDs are made from a variety of inorganic semiconductor materials such as those from aluminum, gallium, silicon, indium, and zinc. They are used to produce different colors, for example, aluminum gallium phosphide is used to produce green LED, aluminum gallium arsenide us used to produce red, and aluminum gallium nitride is used to produce near to far ultraviolet, etc.

Application of LED

They are found in all kinds of devices. For example they form the numbers on digital clocks. When collected together, they form images on jumbo television screens. LED is also used to illuminate a traffic light. Other applications of LEDs can be found in the automotive industries such as indicator lights; fiber optic data transmissions; remote controls which uses infrared-emitting diodes; and backlighting in LCD panels.

Summary

The benefits of LED compared to other forms of illuminating devices such as incandescent or fluorescent include high efficiency and low power requirement and when properly installed can function for decades. While up front, they can be more expensive than incandescent lights but their long-term running cost makes them a better buy. In future, they will compete for an even bigger role in the world of technology.

Source: AZoOptics

 

Date Added: Sep 27, 2007
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