Leds đầy màu sắc

Diode phát ra ánh sáng LED, được phát minh vào năm 1962 trên các thí nghiệm ElectroluminescenceĐược gọi là "diode" bởi vì các bộ phận phát ra ánh sáng được cấu tạo bởi giàu điện tử bán dẫn kết nối với một trong nhiều lỗ khác, lỗ có thể được xem như là các hạt tích điện dương
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Leds đầy màu sắcContents 1. General knowledge about LED 2. The structure 3. Operation principle 4. Colors of LEDWhat is LED? LED- Light emitting diode, was invented in 1962 on electroluminescence experiments Called as “diode” because of the light emitting parts are composed by electron-rich semiconductor connected to the other hole-rich one, the hole can be viewed as positively charged particlesWhat is LED?Nowadays, LEDs are semiconductorlight source used as indicator lamps inmany devices and are increasinglyused for other lighting with thevariability across the visible, ultravioletand infrared wavelengths, and veryhigh brightnessKinds of LEDLow/Medium power LEDs: High power LEDs: used tothe current used isn‟t higher illuminate surfaces andthan 150mA, mostly used to wholeenvironments.obtain light signals or Single chip Power LEDsdecoration and Multi chip Power LEDsStructureStructure: materials The semiconductor gallium arsenide (GaAs) was used in early LEDs. Later, GaP was used as the light-emitter to achieve pale green light. Blue LEDs using silicon carbide (SiC) and ultrabright blue LEDs made of gallium nitride (GaN) Super-bright red. yellow, and green LEDs were produced by using gallium aluminum arsenide phosphide (GaAIAsP). Materials with refractive index that could allow light to „get out‟Operation: electroluminescenceLEDs give off lights on the principle ofelectrical luminescence known aselectroluminescenceOperation When LED is in term of forward- bias Charge-carriers electrons and holes flow into the junction from electrodes with different voltagesOperation When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photonOperation: band gap The band gap of the semicondutor substrate is just right equal to the energy of an emitted photon, that determine the wavelength and color of lightsColors LEDs are available in red, orange, amber, yellow, green, blue and white. Blue and white LEDs are much more expensive than the other coloursColors The color of LED is determined by the semiconductor material, not by the colors of the package ( the plastic body)Colors: monochromaticHuman eye can see light withwavelengths from 380 nm (violetlight) to 720 nm (red light). And thewavelength of the light emitted, andthus its color depends on the bandgap energy of the materials formingthe p-n junction Colors: monochromaticSo if we want a red- light emitting LED wewill design a band gap materials in therange of 1.7 eVThe compound semiconductors of thegallium (Ga) as GaAs, GaAsP AlGaP GAP , , ,InGaN have slot values ​range from 1 eV to3.5 eV and it can emit all colors of visiblelightColors: monochromaticColors: white LEDs There are 2 primary ways of producing high intensity white- light using LEDsColors: white LEDs One is to use individual LEDs that emit three primary colors red, green, and blue and then mix all the colors to form white lightColors: white LEDs That method is called multi- colored white LEDs (sometimes referred to as Red Green Blue LEDs). RGB LEDs need electronic circuits to control the blending and diffussion of different colors