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Automotive lighting

taillightturn signalturn signals
Light-emitting diodes are used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, lighted wallpaper and medical devices.
In 1993, the first LED tail lamps were installed on mass-production automobiles.

Silicon carbide

carborundumSiCSiC-MOSFET
Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide and a cat's-whisker detector.
Electronic applications of silicon carbide such as light-emitting diodes (LEDs) and detectors in early radios were first demonstrated around 1907.

H. J. Round

Captain H. J. RoundHenry RoundRound, H. J.
Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide and a cat's-whisker detector.
He was the first to report observation of electroluminescence from a solid state diode, leading to the discovery of the light-emitting diode.

Oleg Losev

O. V. LosevOleg Vladimirovich Losev
Russian inventor Oleg Losev reported creation of the first LED in 1927.
He observed light emission from carborundum point-contact junctions, the first light-emitting diode (LED), did the first research on them, proposed the first correct theory of how they worked, and used them in practical applications such as electroluminescence.

James R. Biard

In September 1961, while working at Texas Instruments in Dallas, Texas, James R. Biard and Gary Pittman discovered near-infrared (900 nm) light emission from a tunnel diode they had constructed on a GaAs substrate.
Some of his more significant patents include the first infrared light-emitting diode (LED), optical isolators, Schottky clamped logic circuits, silicon Metal Oxide Semiconductor Read Only Memory (MOS ROM), a low bulk leakage current avalanche photodetector, and fiber-optic data links.

Semiconductor

semiconductorssemiconductingsemiconductor material
A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons.
In certain semiconductors, excited electrons can relax by emitting light instead of producing heat. These semiconductors are used in the construction of light-emitting diodes and fluorescent quantum dots.

Gallium arsenide

GaAsgallium-arsenidegallium(III) arsenide
Rubin Braunstein of the Radio Corporation of America reported on infrared emission from gallium arsenide (GaAs) and other semiconductor alloys in 1955.
Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monolithic microwave integrated circuits, infrared light-emitting diodes, laser diodes, solar cells and optical windows.

Nick Holonyak

Nick Holonyak, Jr.Dr. Nicholas Holonyak
The first visible-spectrum (red) LED was developed in 1962 by Nick Holonyak, Jr. while working at General Electric.
He is noted particularly for his 1962 invention of a light-emitting diode (LED) that emitted visible red light instead of infrared light; Holonyak was then working at General Electric's research laboratory in Syracuse, New York.

Laser diode

semiconductor laserdiode laserlaser diodes
Today, magnesium-doping of gallium nitride remains the basis for all commercial blue LEDs and laser diodes.
A laser diode, (LD), injection laser diode (ILD), or diode laser is a semiconductor device similar to a light-emitting diode in which the laser beam is created at the diode's junction.

Electroluminescence

electroluminescentELelectroluminescent panel
Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide and a cat's-whisker detector. This effect is called electroluminescence.
Prior to recombination, electrons and holes may be separated either by doping the material to form a p-n junction (in semiconductor electroluminescent devices such as light-emitting diodes) or through excitation by impact of high-energy electrons accelerated by a strong electric field (as with the phosphors in electroluminescent displays).

M. George Craford

M. George Craford, a former graduate student of Holonyak, invented the first yellow LED and improved the brightness of red and red-orange LEDs by a factor of ten in 1972.
M. George Craford is an American electrical engineer known for his work in Light Emitting Diodes (LEDs).

Seven-segment display

7-segment displayseven segment displayseven-segment
Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays. The first commercial LEDs were commonly used as replacements for incandescent and neon indicator lamps, and in seven-segment displays, first in expensive equipment such as laboratory and electronics test equipment, then later in such appliances as calculators, TVs, radios, telephones, as well as watches (see list of signal uses).
Seven-segment displays may use a liquid crystal display (LCD), a light-emitting diode (LED) for each segment, an electrochromic display, or other light-generating or controlling techniques such as cold cathode gas discharge (Panaplex), vacuum fluorescent, incandescent filaments (Numitron), and others.

Light

visible lightvisiblelight source
A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons.
Emission can be spontaneous, as in light-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc.), and flames (light from the hot gas itself—so, for example, sodium in a gas flame emits characteristic yellow light).

Lighting

illuminationartificial lightartificial lighting
Light-emitting diodes are used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, lighted wallpaper and medical devices.
Recessed lighting (often called "pot lights" in Canada, "can lights" or 'high hats" in the US) is popular, with fixtures mounted into the ceiling structure so as to appear flush with it. These downlights can use narrow beam spotlights, or wider-angle floodlights, both of which are bulbs having their own reflectors. There are also downlights with internal reflectors designed to accept common 'A' lamps (light bulbs) which are generally less costly than reflector lamps. Downlights can be incandescent, fluorescent, HID (high intensity discharge) or LED.

Gallium nitride

GaNgallium nitride (GaN)gallium(III) nitride
In parallel, Isamu Akasaki and Hiroshi Amano in Nagoya were working on developing the important GaN nucleation on sapphire substrates and the demonstration of p-type doping of GaN.
Gallium nitride () is a binary III/V direct bandgap semiconductor commonly used in light-emitting diodes since the 1990s.

Shuji Nakamura

Nakamura, ShujiS. NakamuraShūji Nakamura
Two years later, in 1993, high-brightness blue LEDs were demonstrated by Shuji Nakamura of Nichia Corporation using a gallium nitride growth process similar to Moustakas's.
Shuji Nakamura is a Japanese-born American electronic engineer and inventor specializing in the field of semiconductor technology, professor at the Materials Department of the College of Engineering, University of California, Santa Barbara (UCSB), and is regarded as the inventor of the blue LED, a major breakthrough in lighting technology.

P–n junction

p-n junctionreverse biasjunction
On August 8, 1962, Biard and Pittman filed a patent titled "Semiconductor Radiant Diode" based on their findings, which described a zinc-diffused p–n junction LED with a spaced cathode contact to allow for efficient emission of infrared light under forward bias.
p–n junctions are elementary "building blocks" of semiconductor electronic devices such as diodes, transistors, solar cells, LEDs, and integrated circuits; they are the active sites where the electronic action of the device takes place.

Isamu Akasaki

In parallel, Isamu Akasaki and Hiroshi Amano in Nagoya were working on developing the important GaN nucleation on sapphire substrates and the demonstration of p-type doping of GaN. Nakamura, Hiroshi Amano and Isamu Akasaki were awarded the Nobel Prize in Physics in 2014 for the invention of the blue LED.
Isamu Akasaki is a Japanese physicist, specializing in the field of semiconductor technology and Nobel Prize laureate, best known for inventing the bright gallium nitride (GaN) p-n junction blue LED in 1989 and subsequently the high-brightness GaN blue LED as well.

Neon lamp

neonneon bulbneon lights
The first commercial LEDs were commonly used as replacements for incandescent and neon indicator lamps, and in seven-segment displays, first in expensive equipment such as laboratory and electronics test equipment, then later in such appliances as calculators, TVs, radios, telephones, as well as watches (see list of signal uses).
Glow lamps found practical use as indicators in instrument panels and in many home appliances until the widespread commercialization of light-emitting diodes (LEDs) in the 1970s.

Phosphor

phosphorsP39 phosphorP7 phosphor
Using different phosphors produces green and red light through fluorescence.
Phosphorescent materials are known for their use in radar screens and glow-in-the-dark materials, whereas fluorescent materials are common in cathode ray tube (CRT) and plasma video display screens, fluorescent lights, sensors, and white LEDs.

Monsanto

Monsanto CompanyCalgeneGenuity
The Monsanto Company was the first organization to mass-produce visible LEDs, using gallium arsenide phosphide (GaAsP) in 1968 to produce red LEDs suitable for indicators.
In 1968, it became the first company to start mass production of (visible) light-emitting diodes (LEDs), using gallium arsenide phosphide.

Hiroshi Amano

In parallel, Isamu Akasaki and Hiroshi Amano in Nagoya were working on developing the important GaN nucleation on sapphire substrates and the demonstration of p-type doping of GaN. Nakamura, Hiroshi Amano and Isamu Akasaki were awarded the Nobel Prize in Physics in 2014 for the invention of the blue LED.
For his work he was awarded the 2014 Nobel Prize in Physics together with Isamu Akasaki and Shuji Nakamura for "the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources".

Haitz's law

This trend in increased output has been called Haitz's law after Dr. Roland Haitz.
Haitz's law is an observation and forecast about the steady improvement, over many years, of light-emitting diodes (LEDs).

Nichia

Nichia CorporationNichia labs
Two years later, in 1993, high-brightness blue LEDs were demonstrated by Shuji Nakamura of Nichia Corporation using a gallium nitride growth process similar to Moustakas's.
It specializes in the manufacturing and distribution of phosphors, including light-emitting diodes (LEDs), laser diodes, battery materials, and calcium chloride.

Cerium

CeCe IV
In this device a :Ce (known as "YAG") cerium doped phosphor coating produces yellow light through fluorescence.
Cerium-doped YAG phosphor is used in blue light-emitting diodes to produce white light.