The light emitting diode (LED) are new energy saving and environment-friendly light source.  A LED is made of semiconductor materials.  In spite of other light sources where most of the energy produced by electricity is in the form of heat and there is only a small portion is converted into light.  LED directly converts electrical energy into light particles thus having high efficiency.  In ordinary incandescent lamp, there is a tungsten filament which heated to produce light.  In fluorescent lamps which are previously having a title of low energy, lamps uses a gas discharge to produce heat and light.  But now by the invention of LED lights they have lost their place in day to day life. Thus we understand that LED required less energy to emit light as compared to other sources discussed earlier. With the advancement of technology LED’s are developing in the directions of high flux per unit electrical input power.  Now up to 300 lumen/watt efficient LED’s are available, this can save a large amount of electrical energy and help to save the Earth’s resources.  The life of LED is very high as compare to other incandescent lamps and fluorescent lamps.

The first scientist who studies the emission of light from semiconductors in 1907 was Henry J. Round, a co-worker of Guglielemo Marconi, Nobel Prize Laureate 1909.  After this several attempts were made to understand this electroluminescence.  The red light LED was invented in the end of 1950’s.  They were used in digital watches, calculators or as indicators (ON/OFF) in various devices.  In the early stages scientist known that LED with short wavelength consisting of high energetic photons.  But to produce white light a blue-light light emitting diode was needed.  A light emitting diode is made of several layers of semiconducting materials.  When an electric voltage is applied electrons from the n-layer and holes from the p-layer are driven to the active layer where they recombine and light is emitted.  The wavelength of light emitted depends on the semiconducting material used.  White LED lamps are made in two different manners one ways is to used blue light to excite phosphorus so that it shines in red and green when all colors come together, white light is produced. The other way is to design the lamp out of three LED’s red, green and blue.  These colors combine and produce the effect of white light.

During the 1990’s Isamu Akasaki together with Hiroshi Amano as well as Shuji Nakamura succeeded in further improving their blue LED’s and making them more efficient.  Both the group uses different gallium nitride alloys using aluminium and indium.  For the discovery of Blue light LED they are awarded with the Nobel Prize in Physics in 2014.

To make student update with the continuous advancement in technology we at SISTec providing training on the basic concept of different Diodes in Engineering Physics Lab.  Sagar Group of Institution–SISTec offering a workshop for making LED bulbs for the students of first year and second year.  Along with these workshops we at SISTec prepares different modules based training to train our student on current development in science & engineering in spite of regular RGPV curriculum.


WRITTEN BY:                                                                                                                                                                                Dr. Ashvini Sahu

Department of Physics

Sagar Group of Institutions SISTec Ratibad 




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