Elsevier Science. August 1, 2025. p > 자유게시판

A gentle-emitting diode (LED) is a semiconductor device that emits light when present flows through it. Electrons in the semiconductor recombine with electron holes, releasing power in the form of photons. The coloration of the light (corresponding to the power of the photons) is set by the power required for electrons to cross the band hole of the semiconductor. White mild is obtained by using multiple semiconductors or a layer of mild-emitting phosphor reduce energy consumption on the semiconductor machine. Showing as sensible digital parts in 1962, the earliest LEDs emitted low-intensity infrared (IR) light. Infrared LEDs are used in remote-management circuits, resembling those used with a large variety of consumer electronics. The first seen-mild LEDs were of low intensity and limited to crimson. Early LEDs have been typically used as indicator lamps, changing small incandescent bulbs, EcoLight energy and in seven-phase shows. Later developments produced LEDs out there in seen, ultraviolet (UV), and infrared wavelengths with high, EcoLight energy low, or intermediate mild output; for instance, white LEDs suitable for room and outdoor lighting.

LEDs have additionally given rise to new varieties of shows and sensors, while their excessive switching charges have makes use of in advanced communications technology. LEDs have been utilized in various functions reminiscent of aviation lighting, fairy lights, strip lights, automotive headlamps, EcoLight energy promoting, stage lighting, basic lighting, site visitors indicators, digicam flashes, lighted wallpaper, horticultural grow lights, and medical devices. LEDs have many advantages over incandescent mild sources, together with decrease energy consumption, EcoLight an extended lifetime, improved physical robustness, smaller sizes, and faster switching. In trade for EcoLight energy these typically favorable attributes, disadvantages of LEDs include electrical limitations to low voltage and customarily to DC (not AC) power, the lack to supply steady illumination from a pulsing DC or an AC electrical supply supply, and a lesser most operating temperature and storage temperature. LEDs are transducers of electricity into mild. They function in reverse of photodiodes, which convert mild into electricity. Electroluminescence from a stable state diode was discovered in 1906 by Henry Joseph Round of Marconi Labs, and was revealed in February 1907 in Electrical World.

Spherical noticed that varied carborundum (silicon carbide) crystals would emit yellow, EcoLight smart bulbs mild green, orange, or blue light when a voltage was handed between the poles. From 1968, industrial LEDs had been extremely costly and saw no practical use. In the early 1990s, Shuji Nakamura, Hiroshi Amano and Isamu Akasaki developed blue mild-emitting diodes that had been dramatically more environment friendly than their predecessors, bringing a brand new technology of vivid, vitality-environment friendly white lighting and full-color long-life LED LED shows into practical use. For this work, they gained the 2014 Nobel Prize in Physics. In a light-emitting diode, the recombination of electrons and electron holes in a semiconductor produces light (infrared, visible or UV), a process called electroluminescence. The wavelength of the light depends upon the EcoLight energy band hole of the semiconductors used. Since these supplies have a high index of refraction, design features of the gadgets comparable to special optical coatings and die form are required to effectively emit gentle. Not like a laser, the light emitted from an LED is neither spectrally coherent nor even extremely monochromatic.

Its spectrum is sufficiently narrow that it appears to the human eye as a pure (saturated) shade. Additionally unlike most lasers, its radiation isn't spatially coherent, so it cannot method the very excessive intensity characteristic of lasers. By choice of various semiconductor supplies, single-shade LEDs will be made that emit light in a narrow band of wavelengths, from the close to-infrared through the seen spectrum and into the ultraviolet vary. The required operating voltages of LEDs improve as the emitted wavelengths turn into shorter (greater power, red to blue), due to their increasing semiconductor band EcoLight energy hole. Blue LEDs have an energetic region consisting of a number of InGaN quantum wells sandwiched between thicker layers of GaN, referred to as cladding layers. By various the relative In/Ga fraction in the InGaN quantum wells, the light emission can in idea be various from violet to amber. Aluminium gallium nitride (AlGaN) of varying Al/Ga fraction can be utilized to manufacture the cladding and quantum well layers for ultraviolet LEDs, however these devices haven't yet reached the level of effectivity and technological maturity of InGaN/GaN blue/inexperienced units.

If unalloyed GaN is used on this case to type the active quantum nicely layers, the system emits close to-ultraviolet mild with a peak wavelength centred round 365 nm. Green LEDs manufactured from the InGaN/GaN system are way more efficient and brighter than green LEDs produced with non-nitride materials programs, however sensible devices nonetheless exhibit effectivity too low for high-brightness purposes. With AlGaN and AlGaInN, even shorter wavelengths are achievable. Close to-UV emitters at wavelengths round 360-395 nm are already low cost and EcoLight sometimes encountered, for example, as black mild lamp replacements for inspection of anti-counterfeiting UV watermarks in paperwork and bank notes, and for UV curing. Substantially more expensive, shorter-wavelength diodes are commercially accessible for wavelengths all the way down to 240 nm. As the photosensitivity of microorganisms approximately matches the absorption spectrum of DNA, with a peak at about 260 nm, UV LED emitting at 250-270 nm are anticipated in prospective disinfection and sterilization units. Recent research has proven that commercially available UVA LEDs (365 nm) are already efficient disinfection and sterilization gadgets.