What’s LED (Light Emitting Diode) ?
LED (Light Emitting Diode), LED is a solid-state semiconductor devices, it can direct the light into electricity. The heart of LED chip is a semiconductor chip is attached to one end of a stent, this end is negative, the other end to connect the positive power supply. And the whole package together chip by epoxy resin.
Semiconductor chip is composed of three parts, part of P-type semiconductor, in which the dominant hole inside, the other side of the N-type semiconductor, here is mainly electronic, the middle is usually 1-5 cycles of the quantum well.
When the current through the wire act on the chip, the electrons and holes into the quantum wells will be in the quantum well with electron-hole complex, and then will be issued in the form of photon energy, which is the principle of light-emitting LED. The wavelength of light is the color of light is the formation of PN junction by the decision of the 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:
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Color
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Wavelength (nm)
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Voltage (V)
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Semiconductor Material
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Infrared
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λ > 760
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ΔV < 1.9
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Gallium arsenide (GaAs)
Aluminium gallium arsenide (AlGaAs)
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Red
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610 < λ < 760
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1.63 < ΔV < 2.03
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Aluminium gallium arsenide (AlGaAs)
Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP)
Gallium(III) phosphide (GaP)
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|
Orange
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590 < λ < 610
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2.03 < ΔV < 2.10
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Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP)
Gallium(III) phosphide (GaP)
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|
Yellow
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570 < λ < 590
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2.10 < ΔV < 2.18
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Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP)
Gallium(III) phosphide (GaP)
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Green
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500 < λ < 570
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1.9 < ΔV < 4.0
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Indium gallium nitride (InGaN) / Gallium(III) nitride (GaN)
Gallium(III) phosphide (GaP)
Aluminium gallium indium phosphide (AlGaInP)
Aluminium gallium phosphide (AlGaP)
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Blue
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450 < λ < 500
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2.48 < ΔV < 3.7
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Zinc selenide (ZnSe)
Indium gallium nitride (InGaN)
Silicon carbide (SiC) as substrate
Silicon (Si) as substrate — (under development)
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Violet
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400 < λ < 450
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2.76 < ΔV < 4.0
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Indium gallium nitride (InGaN)
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Purple
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multiple types
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2.48 < ΔV < 3.7
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Dual blue/red LEDs,
blue with red phosphor,
or white with purple plastic
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Ultraviolet
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λ < 400
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3.1 < ΔV < 4.4
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Diamond (235 nm)
Boron nitride (215 nm)
Aluminium nitride (AlN) (210 nm)
Aluminium gallium nitride (AlGaN)
Aluminium gallium indium nitride (AlGaInN) — (down to 210 nm)
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White
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Broad spectrum
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ΔV = 3.5
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Blue/UV diode with yellow phosphor
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05/14/2019
