Light Emitting Diode ( LED ) :
A Light Emitting Diode (LED) is an associate optical conductor that emits lightweight once a voltage is applied. In different words, crystal rectifier is an associate optical conductor that converts current into lightweight energy. lightweight Emitting Diodes (LEDs) area unit the foremost wide used semiconductor diodes among all the various forms of semiconductor diodes out there these days. lightweight emitting diodes emit either actinic radiation or invisible actinic ray once forward biased. The LEDs that emit invisible actinic ray area unit used for remote controls.
This is true of all semiconductor junctions, however, LEDs use materials that maximize the result. the DS of the sunshine emitted is set by the semiconductor materials that type the diode junction. just like the traditional tangency diodes, LEDs additionally operates solely in forwarding bias condition. to form associate crystal rectifier, the n-type material ought to be connected to the negative terminal of the battery and p-type material ought to be connected to the positive terminal of the battery. In different words, the n-type material ought to be charged and also the p-type material ought to be charged.
LED Working Principle :
- Light Emitting Diode (LED) works solely in an exceedingly forward bias condition. once lightweight Emitting Diode (LED) is forward biased, the free electrons from n-side and also the holes from p-side square measure pushed towards the junction.
- The light emitting diode merely, we all know as a diode. once the diode is forward biased, then the electrons & holes square measure moving quick across the junction and that they square measure combining perpetually, removing each other out.
- before long when the electrons square measure moving from the n-type to the p-type Si, it combines with the holes, then it disappears.
- The rule of the sunshine emitting diode is predicated on scientific theory. The scientific theory says that once the negatron comes down from the upper energy state to the lower energy state then, the energy emits from the gauge boson.
- The gauge boson energy is up to the energy gap between these 2 energy levels. If the PN-junction diode is within the forward biased, then this flows through the diode.
- The recombination indicates that the electrons within the physical phenomenon band jump right down to the valence band. once the electrons jump from one band to a different band the electrons can emit the magnetism energy within the kind of gauge bosons and also the photon energy is up to the tabu energy gap.
- Thus, recombination takes place in depletion region further as in p-type and semiconductor unit.
- The free electrons within the physical phenomenon band unharness energy within the sort of lightweight before they recombine with holes within the valence band.
- In semiconductor and Ge diodes, most of the energy is discharged within the sort of heat and emitted lightweight is simply too little.
- Ge semiconductors this proscribed energy gap is between the condition and valence bands area unit specified the full radiation of electromagnetic radiation throughout recombination is within the sort of the actinic ray.
I-V Characteristics of LED :
There area unit differing kinds of lightweight of sunshine emitting diodes area unit out there within the market and their area unit totally different crystal rectifier characteristics that embody the colour light, or wavelength radiation, candlepower. The necessary characteristic of the crystal rectifier is colour. within the beginning use of crystal rectifier, there’s the sole red colour. because the crystal rectifier is to be connected associate exceedingly in a very forward bias condition across an influence provide it ought to be presently restricted employing a series electrical device to shield it from an excessive current flow. ne’er connect associate degree crystal rectifier on to electric battery or power provide because it is destroyed virtually instantly as a result of an excessive amount of current can taste and burn it out.
In most cases, LEDs area unit operated from an occasional voltage DC provide, with a series electrical device, RS wont to limit the forward current to a secure price from saying 5mA for a straightforward crystal rectifier indicator to 30mA or a lot of wherever a high brightness light-weight output is required.