LED Light

Light emission diode (LED) is a semiconductor that emits incoherent monochromatic light when given a forward voltage.
These symptoms include electroluminesense form. The resulting color depends on the semiconducting material used, and can be near ultraviolet or near infrared.

Physical function

An LED is a special type of semiconductor diode. Like a normal diode, the LED consists of a chip of semiconducting material that is fully charged, or in-dop, with impurities to create a structure called a pn junction. Charge-carriers - electrons and holes flow into the junction from electrodes with different voltage. When an electron meets a hole, he fell into a lower energy level, and release energy in the form of photons.

Emission of light

The wavelength of light emitted, and therefore its color, depends on the difference in the energy band of material forming a pn junction. A normal diode, typically made ??of silicon or germanium, emits visible light near infrared, but the material used for an LED lamp have a difference between the energy band near-infrared light, visible, and near ultraviolet.

Polarization

Unlike incandescent and fluorescent lamps, LED light light have a tendency of polarization. LED chip has a positive pole and negative (pn) and will only light up when given forward current. This is because LED light are made from semiconductor materials that will only allow electric current to flow in one direction and not in the opposite direction. When given current LED reverse, there would be little current through the LED chip. This causes the LED chip will not emit light.

Chip LEDs generally have relatively low voltage damage. When given voltage a few volts reverse direction, usually the nature of the insulator in the direction of the LED will be broken causing a current to flow in the opposite direction.

The voltage developed

Characteristics of LED chips in general are the same as the characteristics of the diode which only requires a certain voltage to operate. But when given a voltage that is too large, the LED will be damaged even though the applied voltage is the forward voltage.
Voltage required to operate a diode is forward voltage (Vf).

LED Circuit

LED circuits can be designed by arranging the LEDs in series or parallel position. When arranged in series, then that needs to be considered is the amount of voltage required all LEDs in the series earlier. However, if the LED is placed in parallel circumstances, it is to note the amount of current required throughout the LEDs in this circuit.

Develop LEDs in series would be more difficult if the color of the LED is different, because each has a different color LED forward voltage (Vf) are different. This difference would cause if the amount of voltage supplied by power source is insufficient to LED chips, then some of the LEDs will not light up. Conversely, when the applied voltage is too large will result in damage to the LEDs that have a relatively low forward voltage.

In general, LED light are arranged in series must have a forward voltage of the same or at least not much different from the circuit so that this LED light can work well. If the LED light is used for the indicator at a higher voltage than its operations coupled in series with a resistor to adjust the flow so as not to exceed the LED light maximum current, maximum current when the LED goes bad too.

LED Substrates

LED development began with infrared and red devices made with gallium arsenide. Development in materials science have enabled the production of tools with shorter wavelengths, producing light with varied colors.
Conventional LED are made of inorganic minerals are varied, producing a color as follows:
aluminum gallium arsenide (AlGaAs) - red and infrared
gallium aluminum phosphide - green
gallium arsenide / phosphide (GaAsP) - red, orange-red, orange, and yellow
gallium nitride (GaN) - green, pure green (or emerald green), and blue
gallium phosphide (GaP) - red, yellow, and green
zinc selenide (ZnSe) - blue
indium gallium nitride (InGaN) - bluish green and blue
aluminum gallium indium phosphide - orange-red, orange, yellow, and green
silicon carbide (SiC) - blue
diamond (C) - ultraviolet
silicon (Si) - Blue (in development)
sapphire (Al2O3) - blue

Blue and white LED

The first blue LEDs that can reach commercial information using gallium nitride substrates that are found by Shuji Nakamura in 1993 during a career at Nichia Corporation in Japan. LED was then popular in the late 90’s. Blue LEDs can be combined into the red and green LEDs that have been there before to create white light.

LED light bulbs with white light is now the majorities are made by coating a substrate of gallium nitride (GaN) with yellow phosphorus. Because the color yellow stimulates the red and green receivers in the human eye, the color combination of yellow and blue phosphors of the substrate will give the impression of a white color for the human eye.

White LEDs can also be made by coating the phosphor blue, red and green in the substrate near ultraviolet is more or less similar to the way fluorescent lamps work.

Current methods for creating white light from LEDs is by not using phosphorus at all but uses a zinc selenide substrate that can emit blue light from the active area and the yellow light from the substrate itself.