LED Characteristes or Forward characteristics of LEA OF VI. 1-3 3.3 (For Gro AS) LED will emit the light when property biased Principle:- Electroluminescene The best electroluminescene device is LEN. In LED, light is emitted due to a large number of recombinations at the junction. In LE most of the eight is concentrated near the junction because charge carrieros are within the diffusion length (so that i's & boler the junction). energy is released to → Generally fabricated with BBG Semiconductor. Properly used material los GIGAS. Depending on the material used, LEDs can emit light in the visible or invisible spectrum. In the invisible spectrum, LED emits infrared light IR LED is used as a remote control trans- -mitter In the visible ispectrum of light LED can emit any one of the following colours like Red, Green, Orange, Yellow, white, amber the colour of light given by Les depends on (1) The wavelength & frequency of the radiated Sight 1= 1.24 = Um (11) The type and conc. of dopant - LED fabricated with GaAs which emit IR light LER materials are GIGAS, GIOASP, Grap Modern LED are fabricated with ABGScand Some of IBG semiconductor under control doping ל Always undere operated forward bias With 20mA of forward current LED gives out the max. intensity of light → When forward current increases from oto 20mA, the efficiency of LED will be increasing T'e. it will emit more brightness, of ligra Efficiency of LEN & forward current (If) If forward current ius more than 20mA, th junction temperature increases and LEN can heated up & the efficiency decreases ie it will cmit dull colowe light temperatwe when reverse bias, LED working as normal diode and therefore it will not emit any light Power dissipation (I2R loss) (internal power consumal i's milliwatt Larger operating life (1,00,000 + hrs) Response time in usec. Cut in voltage dopant (1-3V-1.5V) depending on Larger carrier life time when compare to ha LEN ios faster than LCD, because of smaller veesponse time → When compared to Low, the disadvantage of LED is higher powere dissipation. Applications... Aus a remote control transmittere As a display clevice. In desigring of opto couplers.