10906497 term paper
Post on 03-Apr-2018
215 Views
Preview:
TRANSCRIPT
-
7/28/2019 10906497 Term Paper
1/22
Term Paper
ELECTRONICS DEVICE AND CIRCUIT
Submitted by:
JAGBEER YADAV
Roll No. : A05
Section : D6905
Regd. No. : 10906497
Submitted to:
MISS NIDHI MADAM
(ELECTRONICS DEPT.)
-
7/28/2019 10906497 Term Paper
2/22
TOPIC:-
LIGHT EMITTING DIODE
-
7/28/2019 10906497 Term Paper
3/22
Light-emitting diode
Blue, green, and red LEDs; these can be combined to produce most perceptible colors,
including white.
Infrared and ultraviolet (UVA) LEDs are also available.
A light-emitting-diode (LED) is a semiconductor diode that emits light when an electric
current is applied in the forward direction of the device, as in the simple LED circuit. The
effect is a form of electroluminescence where incoherent and narrow-spectrum light is
emitted from thep-n junction.
LEDs are widely used as indicator lights on electronic devices and increasingly in higherpower applications such as flashlights and area lighting. An LED is usually a small area (less
than 1 mm2) light source, often with optics added to the chip to shape its radiation pattern and
assist in reflection. The colorof the emitted light depends on the composition and condition
of the semiconducting material used, and can be infrared, visible, or ultraviolet. Besides
lighting, interesting applications include using UV-LEDs for sterilization of water and
disinfection of devices,[4] and as agrow light to enhancephotosynthesis in plants.
http://en.wikipedia.org/wiki/Semiconductor_diodehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/LED_circuithttp://en.wikipedia.org/wiki/Electroluminescencehttp://en.wikipedia.org/wiki/Coherence_(physics)http://en.wikipedia.org/wiki/Spectrumhttp://en.wikipedia.org/wiki/P-n_junctionhttp://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Colorhttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Visible_spectrumhttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/UVhttp://en.wikipedia.org/wiki/LED#cite_note-water-3http://en.wikipedia.org/wiki/Grow_lighthttp://en.wikipedia.org/wiki/Grow_lighthttp://en.wikipedia.org/wiki/Photosynthesishttp://en.wikipedia.org/wiki/Image:LED_symbol.svghttp://en.wikipedia.org/wiki/Image:RBG-LED.jpghttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/LED_circuithttp://en.wikipedia.org/wiki/Electroluminescencehttp://en.wikipedia.org/wiki/Coherence_(physics)http://en.wikipedia.org/wiki/Spectrumhttp://en.wikipedia.org/wiki/P-n_junctionhttp://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Colorhttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Visible_spectrumhttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/UVhttp://en.wikipedia.org/wiki/LED#cite_note-water-3http://en.wikipedia.org/wiki/Grow_lighthttp://en.wikipedia.org/wiki/Photosynthesishttp://en.wikipedia.org/wiki/Semiconductor_diode -
7/28/2019 10906497 Term Paper
4/22
HistoryDiscovery and development
The first known report of a light-emitting solid-state diode was made in 1907 by the British
experimenter H. J. Round of Marconi Labs. Russian Oleg Vladimirovich Losev
independently created the first LED in the mid 1920s; his research, though distributed in
Russian, German and British scientific journals, was ignored, and no practical use was made
of the discovery for several decades. Rubin Braunstein of the Radio Corporation of America
reported on infrared emission from gallium arsenide (GaAs) and other semiconductor alloys
in 1955. Braunstein observed infrared emission generated by simple diode structures using
GaSb, GaAs, InP, and Ge-Si alloys at room temperature and at 77 K. In 1961, experimenters
Bob Biard and Gary Pittman working at Texas Instruments, found that gallium arsenide gave
off infrared radiation when electric current was applied. Biard and Pittman were able to
establish the priority of their work and received the patent for the infrared light-emitting
diode.
The first practical visible-spectrum (red) LED was developed in 1962 byNick Holonyak Jr.,
while working at General Electric Company. He later moved to the University of Illinois at
Urbana-Champaign. Holonyak is seen as the "father of the light-emitting diode". M. George
Craford, a former graduate student of Holonyak's, invented the first yellow LED and 10x
brighter red and red-orange LEDs in 1972.
Shuji Nakamura ofNichia Corporation of Japan demonstrated the first high-brightness blue
LED based on InGaN borrowing on critical developments in GaN nucleation on sapphire
substrates and the demonstration of p-type doping of GaN which were developed by I.
Akasaki and H. Amano in Nagoya. In 1995, Alberto Barbieri at the Cardiff University
Laboratory (GB) investigated the efficiency and reliability of high-brightness LEDs
demonstrating very high result by using a transparent contact made of indium tin oxide (ITO)
on (AlGaInP/GaAs) LED. The existence of blue LEDs and high efficiency LEDs quickly led
to the development of the first white LED, which employed a Y 3Al5O12:Ce, or "YAG",
phosphor coating to mix yellow (down-converted) light with blue to produce light that
appears white. Nakamura was awarded the 2006 Millennium Technology Prize for hisinvention.
The development of LED technology has caused their efficiency and light output to increase
exponentially, with a doubling occurring about every 36 months since the 1960s, in a similar
way to Moore's law. The advances are generally attributed to the parallel development of
other semiconductor technologies and advances in optics and material science. This trend is
normally called Haitz's Law after Dr. Roland Haitz.
http://en.wikipedia.org/wiki/H._J._Roundhttp://en.wikipedia.org/wiki/Marconi_Labshttp://en.wikipedia.org/wiki/Oleg_Vladimirovich_Losevhttp://en.wikipedia.org/w/index.php?title=Rubin_Braunstein&action=edit&redlink=1http://en.wikipedia.org/wiki/Radio_Corporation_of_Americahttp://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Gallium_antimonidehttp://en.wikipedia.org/wiki/GaAshttp://en.wikipedia.org/wiki/Indium_phosphidehttp://en.wikipedia.org/wiki/Texas_Instrumentshttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Nick_Holonyakhttp://en.wikipedia.org/wiki/General_Electric_Companyhttp://en.wikipedia.org/wiki/General_Electric_Companyhttp://en.wikipedia.org/wiki/University_of_Illinois_at_Urbana-Champaignhttp://en.wikipedia.org/wiki/University_of_Illinois_at_Urbana-Champaignhttp://en.wikipedia.org/wiki/Shuji_Nakamurahttp://en.wikipedia.org/wiki/Nichia_Corporationhttp://en.wikipedia.org/wiki/Indium_gallium_nitridehttp://en.wikipedia.org/wiki/Gallium_nitridehttp://en.wikipedia.org/wiki/Nagoyahttp://en.wikipedia.org/w/index.php?title=Alberto_Barbieri&action=edit&redlink=1http://en.wikipedia.org/wiki/Cardiff_Universityhttp://en.wikipedia.org/wiki/Indium_tin_oxidehttp://en.wikipedia.org/wiki/YAGhttp://en.wikipedia.org/wiki/Millennium_Technology_Prizehttp://en.wikipedia.org/wiki/Exponentiallyhttp://en.wikipedia.org/wiki/Exponentiallyhttp://en.wikipedia.org/wiki/Moore's_lawhttp://en.wikipedia.org/wiki/Haitz's_Lawhttp://en.wikipedia.org/wiki/H._J._Roundhttp://en.wikipedia.org/wiki/Marconi_Labshttp://en.wikipedia.org/wiki/Oleg_Vladimirovich_Losevhttp://en.wikipedia.org/w/index.php?title=Rubin_Braunstein&action=edit&redlink=1http://en.wikipedia.org/wiki/Radio_Corporation_of_Americahttp://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Gallium_antimonidehttp://en.wikipedia.org/wiki/GaAshttp://en.wikipedia.org/wiki/Indium_phosphidehttp://en.wikipedia.org/wiki/Texas_Instrumentshttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Nick_Holonyakhttp://en.wikipedia.org/wiki/General_Electric_Companyhttp://en.wikipedia.org/wiki/University_of_Illinois_at_Urbana-Champaignhttp://en.wikipedia.org/wiki/University_of_Illinois_at_Urbana-Champaignhttp://en.wikipedia.org/wiki/Shuji_Nakamurahttp://en.wikipedia.org/wiki/Nichia_Corporationhttp://en.wikipedia.org/wiki/Indium_gallium_nitridehttp://en.wikipedia.org/wiki/Gallium_nitridehttp://en.wikipedia.org/wiki/Nagoyahttp://en.wikipedia.org/w/index.php?title=Alberto_Barbieri&action=edit&redlink=1http://en.wikipedia.org/wiki/Cardiff_Universityhttp://en.wikipedia.org/wiki/Indium_tin_oxidehttp://en.wikipedia.org/wiki/YAGhttp://en.wikipedia.org/wiki/Millennium_Technology_Prizehttp://en.wikipedia.org/wiki/Exponentiallyhttp://en.wikipedia.org/wiki/Moore's_lawhttp://en.wikipedia.org/wiki/Haitz's_Law -
7/28/2019 10906497 Term Paper
5/22
Practical use
The first commercial LEDs were commonly used as replacements for incandescent
indicators, and in seven-segment displays, first in expensive equipment such as laboratory
and electronics test equipment, then later in such appliances as TVs, radios, telephones,
calculators, and even watches (see list of signal applications). These red LEDs were brightenough only for use as indicators, as the light output was not enough to illuminate an area.
Later, other colors became widely available and also appeared in appliances and equipment.
As the LED materials technology became more advanced, the light output was increased,
while maintaining the efficiency and the reliability to an acceptable level, causing LEDs to
become bright enough to be used for illumination, in various applications such as lamps and
other lighting fixtures.
Most LEDs were made in the very common 5 mm T1 and 3 mm T1 packages, but withhigher power, it has become increasingly necessary to shed excess heat in order to maintain
reliability, so more complex packages adapted for efficient heat dissipation are becoming
common. Packages for state-of-the-art high power LEDs bear little resemblance to early
LEDs.
LED technology
Physical principles
The inner workings of an LED
http://en.wikipedia.org/wiki/Incandescencehttp://en.wikipedia.org/wiki/Seven-segment_displayhttp://en.wikipedia.org/wiki/Led#Indicators_and_signshttp://en.wikipedia.org/wiki/Led#Lightinghttp://en.wikipedia.org/wiki/Led#High_power_LEDshttp://en.wikipedia.org/wiki/Image:Rectifier_vi_curve.GIFhttp://en.wikipedia.org/wiki/Image:PnJunction-LED-E.PNGhttp://en.wikipedia.org/wiki/Incandescencehttp://en.wikipedia.org/wiki/Seven-segment_displayhttp://en.wikipedia.org/wiki/Led#Indicators_and_signshttp://en.wikipedia.org/wiki/Led#Lightinghttp://en.wikipedia.org/wiki/Led#High_power_LEDs -
7/28/2019 10906497 Term Paper
6/22
Like a normal diode, the LED consists of a chip of semiconducting material impregnated, or
doped, with impurities to create a p-n junction. As in other diodes, current flows easily from
the p-side, oranode, to the n-side, orcathode, but not in the reverse direction. Charge-carriers
electrons and holesflow into the junction from electrodes with different voltages. Whenan electron meets a hole, it falls into a lowerenergy level, and releases energy in the form of
aphoton.
The wavelength of the light emitted, and therefore its color, depends on the band gap energy
of the materials forming the p-n junction. In silicon orgermanium diodes, the electrons and
holes recombine by a non-radiative transition which produces no optical emission, because
these are indirect band gap materials. The materials used for the LED have a direct band gap
with energies corresponding to near-infrared, visible or near-ultraviolet light.
LED development began with infrared and red devices made with gallium arsenide.
Advances in materials science have made possible the production of devices with ever-
shorterwavelengths, producing light in a variety of colors.
LEDs are usually built on an n-type substrate, with an electrode attached to the p-type layer
deposited on its surface. P-type substrates, while less common, occur as well. Many
commercial LEDs, especially GaN/InGaN, also usesapphiresubstrate.
Colors and Materials
Conventional LEDs are made from a variety of inorganic semiconductor materials, the
following table shows the available colors with wavelength range, voltage drop and material:
ColorWavelength
(nm)Voltage (V) Semi-conductor Material
Infrared > 760 V < 1.9Gallium arsenide (GaAs)
Aluminium gallium arsenide (AlGaAs)
Red 610 < < 1.63 < VAluminium gallium arsenide (AlGaAs)
http://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Doping_(semiconductor)http://en.wikipedia.org/wiki/P-n_junctionhttp://en.wikipedia.org/wiki/Anodehttp://en.wikipedia.org/wiki/Cathodehttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Electron_holehttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Energy_levelhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Band_gaphttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Germaniumhttp://en.wikipedia.org/wiki/Indirect_band_gaphttp://en.wikipedia.org/wiki/Direct_band_gaphttp://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Materials_sciencehttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Sapphirehttp://en.wikipedia.org/wiki/Sapphirehttp://en.wikipedia.org/wiki/Sapphirehttp://en.wikipedia.org/wiki/Semiconductor_materialshttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Delta_(letter)http://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Aluminium_gallium_arsenidehttp://en.wikipedia.org/wiki/Redhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Aluminium_gallium_arsenidehttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Doping_(semiconductor)http://en.wikipedia.org/wiki/P-n_junctionhttp://en.wikipedia.org/wiki/Anodehttp://en.wikipedia.org/wiki/Cathodehttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Electron_holehttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Energy_levelhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Band_gaphttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Germaniumhttp://en.wikipedia.org/wiki/Indirect_band_gaphttp://en.wikipedia.org/wiki/Direct_band_gaphttp://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Materials_sciencehttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Sapphirehttp://en.wikipedia.org/wiki/Semiconductor_materialshttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Delta_(letter)http://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Aluminium_gallium_arsenidehttp://en.wikipedia.org/wiki/Redhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Aluminium_gallium_arsenide -
7/28/2019 10906497 Term Paper
7/22
760 < 2.03
Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide
(AlGaInP)
Gallium(III) phosphide (GaP)
Orange590
top related