Elsevier Science. August 1, 2025. p > 자유게시판

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A mild-emitting diode (LED) is a semiconductor device that emits mild when current flows by way of it. Electrons in the semiconductor recombine with electron holes, releasing vitality in the form of photons. The color of the sunshine (corresponding to the energy of the photons) is decided by the energy required for electrons to cross the band gap of the semiconductor. White gentle is obtained through the use of a number of semiconductors or a layer of gentle-emitting phosphor on the semiconductor gadget. Showing as sensible electronic components in 1962, the earliest LEDs emitted low-depth infrared (IR) light. Infrared LEDs are used in distant-management circuits, corresponding to those used with a wide number of client electronics. The primary seen-light LEDs were of low intensity and LED bulbs for home limited to purple. Early LEDs have been often used as indicator lamps, replacing small incandescent bulbs, and EcoLight dimmable in seven-section displays. Later developments produced LEDs out there in seen, ultraviolet (UV), and infrared wavelengths with high, low, or intermediate gentle output; as an illustration, white LEDs suitable for room and outside lighting.

LEDs have also given rise to new varieties of displays and EcoLight dimmable sensors, whereas their high switching rates have uses in advanced communications technology. LEDs have been used in diverse purposes equivalent to aviation lighting, fairy lights, strip lights, automotive headlamps, advertising, stage lighting, general lighting, traffic alerts, digicam flashes, EcoLight dimmable lighted wallpaper, horticultural develop lights, and medical units. LEDs have many advantages over incandescent light sources, together with lower energy consumption, an extended lifetime, improved physical robustness, smaller sizes, and faster switching. In alternate for these typically favorable attributes, EcoLight dimmable disadvantages of LEDs embody electrical limitations to low voltage and usually to DC (not AC) power, the lack to offer steady illumination from a pulsing DC or an AC electrical supply source, and a lesser most operating temperature and storage temperature. LEDs are transducers of electricity into light. They operate in reverse of photodiodes, which convert light into electricity. Electroluminescence from a stable state diode was discovered in 1906 by Henry Joseph Spherical of Marconi Labs, and was printed in February 1907 in Electrical World.

Spherical observed that various carborundum (silicon carbide) crystals would emit yellow, light green, orange, or blue light when a voltage was handed between the poles. From 1968, industrial LEDs were extraordinarily pricey and saw no practical use. In the early nineteen nineties, Shuji Nakamura, EcoLight dimmable Hiroshi Amano and Isamu Akasaki developed blue gentle-emitting diodes that had been dramatically extra efficient than their predecessors, bringing a brand new technology of brilliant, EcoLight energy vitality-environment friendly white lighting and full-colour LED displays into practical use. For this work, they gained the 2014 Nobel Prize in Physics. In a gentle-emitting diode, the recombination of electrons and electron holes in a semiconductor produces mild (infrared, visible or UV), a process referred to as electroluminescence. The wavelength of the sunshine depends on the vitality band gap of the semiconductors used. Since these supplies have a excessive index of refraction, design options of the units akin to particular optical coatings and die shape are required to effectively emit gentle. In contrast to a laser, the light emitted from an LED is neither spectrally coherent nor even highly monochromatic.

Its spectrum is sufficiently narrow that it appears to the human eye as a pure (saturated) colour. Also unlike most lasers, its radiation shouldn't be spatially coherent, so it cannot approach the very excessive intensity characteristic of lasers. By selection of different semiconductor materials, EcoLight single-shade LEDs can be made that emit mild in a narrow band of wavelengths, from the close to-infrared by the visible spectrum and into the ultraviolet vary. The required working voltages of LEDs increase because the emitted wavelengths turn into shorter (greater energy, EcoLight brand crimson to blue), due to their growing semiconductor band hole. Blue LEDs have an active region consisting of one or more InGaN quantum wells sandwiched between thicker layers of GaN, called cladding layers. By various the relative In/Ga fraction within the InGaN quantum wells, the light emission can in concept be various from violet to amber. Aluminium gallium nitride (AlGaN) of various Al/Ga fraction can be utilized to manufacture the cladding and quantum effectively layers for ultraviolet LEDs, but these units have not but reached the extent of effectivity and technological maturity of InGaN/GaN blue/green devices.

If unalloyed GaN is used on this case to type the active quantum nicely layers, the system emits close to-ultraviolet light with a peak wavelength centred round 365 nm. Inexperienced LEDs manufactured from the InGaN/GaN system are far more environment friendly and brighter than inexperienced LEDs produced with non-nitride material methods, however practical gadgets nonetheless exhibit efficiency too low for top-brightness applications. With AlGaN and AlGaInN, even shorter wavelengths are achievable. Near-UV emitters at wavelengths around 360-395 nm are already low-cost and often encountered, for instance, as black mild lamp replacements for inspection of anti-counterfeiting UV watermarks in documents and bank notes, and for UV curing. Considerably more expensive, EcoLight dimmable shorter-wavelength diodes are commercially obtainable for wavelengths all the way down to 240 nm. As the photosensitivity of microorganisms roughly matches the absorption spectrum of DNA, with a peak at about 260 nm, EcoLight dimmable UV LED emitting at 250-270 nm are expected in prospective disinfection and sterilization devices. Recent research has proven that commercially accessible UVA LEDs (365 nm) are already effective disinfection and sterilization devices.