Chip is a solid-state semiconductor devices, it can be directly put DianZhuan into light. The heart of the LED is a semiconductor chip, chip attached on a bracket, at the end of the end is negative, the other end connected to the power of the anode, the whole chip is encapsulated by epoxy resin.Theoretically, the bigger the chip, can withstand the greater the current, and power; But the chip material and process are the main factors influencing the power of chip size.
Also known as the led chip, is the core of the led components, is refers to the P - N junction. Its main functions are: to convert electrical energy into light energy, the main material of the monocrystalline silicon chip. Semiconductor chip consists of two parts, one part is a p-type semiconductor, dominated by holes in it, the other end is n-type semiconductor, here is mainly electronic. But this two kinds of semiconductor connected, forming a p-n junction between them. When a current flows through a wire to the chip, the electron will be pushed P area, electron and holes in the P zone compound, then will be issued in the form of photon energy, this is the principle of LED. And the wavelength of light was the color of the light, is determined by the formation of p-n junction material.
50 years ago people have to understand semiconductor materials can produce light of the basic knowledge, in 1962, general electric (ge), Nick He Lun ark (Nick HolonyakJr.) developed the first practical application of visible light leds. Leds are English light emitting diode (LED), its basic structure is an electroluminescent semiconductor materials, placed in a wire rack, then sealed with epoxy resin around, namely solid encapsulation, so can protect the internal core, so the LED seismic performance is good.
Initially LED is used as the indicator light instrument and then all kinds of light color of LED traffic light and display screen has been widely applied in large area, produced good economic and social benefits. 12-inch red traffic lights, for example, in the United States could have been used long life and low light efficiency of 140 - watt incandescent lamp as light source, it produces 2000 lumens of white light. After the red filter, light loss 90%, only 200 lumens of red light. And in the light of the new design, Lumileds companies adopted 18 red LED light source, including circuit loss, total power consumption of 14 watts, can produce the same light. Car light is also an important field of LED light source.
1, positive If working current
It refers to the light-emitting diodes normal glowing positive current value. In be used actually shall be according to the need to select the IF below 0.6 · IFm.
2, positive working voltage VF
Parameters of the working voltage is given in the table at a given positive electrical flow. Is usually measured during the IF = 20 ma. Light emitting diodes are working voltage VF in 1.4 ~ 3 v. At higher temperatures in the world and the VF will decline. 
3, V - I characteristic
Light-emitting diodes of the relationship between voltage and current in the forward voltage is less than a certain value (called threshold), small current, light. When the voltage exceeds a certain value, after the forward current voltage increase rapidly, glow.
4, luminous intensity IV
The luminous intensity of light-emitting diodes, often referred to as normal () refers to the axis of cylindrical luminous tubes direction of luminous intensity. If the radiation intensity in the direction of (1/683) W/sr, glow, 1 candela (symbol for CD). As a result of the general LED light-emitting diodes, intensity is small, so the luminous intensity commonly used candles (candela, MCD) as a unit.
5, the LED light Angle
- 90 ° - + 90 °
6 and a half, spectral width Δ lambda
It said light-emitting tube spectral purity.
7 1/2 and perspective, half value Angle theta
Theta 1/2 refers to half of the axial intensity is a luminous intensity value direction and Angle of optical axis to the (normal).
8, the whole shape
According to the LED solid Angle conversion from point of view, also called plane Angle.
9 and perspective
Refers to the maximum Angle of LED, according to the Angle of view is different, have different application, also called Angle of light intensity.
10 and a half
Method to 0 ° and the Angle between the maximum luminous intensity / 2. Strictly speaking, is the maximum luminous intensity and maximum luminous intensity / 2 corresponding Angle. LED packaging technology, leading to the biggest light Angle is not normal light intensity value of 0 °, introducing the deviation Angle, referring to is the luminous intensity corresponding to the Angle of the largest and the method to the Angle between 0 °.
11, maximum positive IFm dc current
Allowed to add one of the biggest positive dc current. More than this value can damage the diodes.
12, the largest reverse voltage VRm
The biggest reverse voltage is allowed to add the breakdown voltage. More than this value, light-emitting diodes can be broken down.
13 topm, work environment
Light-emitting diodes working environment temperature range. Below or above this temperature range, light-emitting diodes will not work properly, the efficiency is greatly reduced.
14 and allow power Pm
Allowed to add to the LED on both ends of the positive dc voltage and current flow through the maximum value of product. More than this value, LED fever, damage.
1、LPE：Liquid Phase Epitaxy GaP/GaP
2、VPE：Vapor Phase Epitaxy GaAsP/GaAs
3、MOVPE：Metal Organic Vapor Phase Epitaxy AlGaInP、GaN
4、SH：GaAlAs/GaAs Single Heterostructure GaAlAs/GaAs
5、DH：GaAlAs/GaAs Double Heterostructure， GaAlAs/GaAs
6、 DDH：GaAlAs/GaAlAs Double Heterostructure， GaAlAs/GaAlAs
Characteristics of the led
(1) four yuan chip, using the MOVPE process preparation, brightness relative to the conventional chips light.
(2) good reliability.
(3) is used widely.
(4) high safety.
(5) the long service life.