Main parameters and structure of LED

LED The main parameters and structure of LED are introduced
We know ,LED The main function of the chip is ： Can directly convert electricity into light , It can be said to be LED The heart of the . This article briefly introduces LED The basic knowledge of chip is ：LED Chip classification 、 structure 、 Features and important parameters .LED Chip is a semiconductor light emitting device LED The core components of (LED The lamp ),LED The principle of luminescence mainly lies in LED Chip P-N junction . Generally speaking , A semiconductor chip consists of two parts , Part of it is P Type semiconductor , In it, holes dominate , The other end is N Type semiconductor , It's mainly electrons here . But when the two semiconductors are connected , They form a P-N junction (LED TV ). When an electric current acts on the chip through a wire , Electrons will be pushed P District , stay P Electrons and holes recombine in the region , Then it will emit energy in the form of photons, and the wavelength of light is the color of light , Is formed by P-N The material of the knot determines (LED Monitor ).
LED The chip is mainly made of arsenic (AS)、 aluminum (AL)、 gallium (Ga)、 indium (IN)、 phosphorus §、 nitrogen (N)、 strontium (Si) Several of these elements make up , The main material is monocrystalline silicon .

LED Chip classification
purpose ： According to the purpose, it is divided into high-power LED chip 、 Small power LED There are two kinds of chips ;
Color ： There are mainly three kinds of ： Red 、 green 、 Blue ( The raw material for making white light );
shape ： Generally divided into square pieces 、 There are two kinds of discs ;
size ： Low power chips are generally divided into 8mil、9mil、12mil、14mil etc.
LED Introduction to chip structure
Different LED chip , Its structure is similar , There is a chip substrate for epitaxy ( Sapphire substrate 、 Silicon carbide substrate, etc ) And doped epitaxial semiconductor materials and transparent metal electrodes .
LED Chip features
1、 Quad chip , use MOVPE Process preparation , The brightness is brighter than that of conventional chips .
2、 Excellent reliability .
3、 Widely applied .
4、 High safety .
5、 Long life .
LED Important parameters of the chip
1、 Forward operating current If：
It refers to the forward current value when the LED emits light normally . In actual use, we should choose... According to needs IF stay 0.6·IFm following .
2、 Forward working voltage VF：
The working voltage given in the parameter table is obtained under a given forward current . Usually in IF=20mA It's measured when . Forward working voltage of LED VF stay 1.4～3V. When the outside temperature rises ,VF It will fall .
3、V-I characteristic ：
Relationship between voltage and current of light emitting diodes , When the forward voltage is less than a certain value ( Called threshold ) when , Minimal current , Non luminous . When the voltage exceeds a certain value , The forward current increases rapidly with voltage , Luminescence .
4、 Luminous intensity IV：
The luminous intensity of light-emitting diodes usually refers to the normal line ( For a cylindrical light emitting tube, it refers to its axis ) Luminous intensity in the direction . If the radiation intensity in this direction is (1/683)W/sr when , Then it glows 1 Candela ( The symbol is cd). Because of the general LED The intensity of LED is small , So the luminous intensity is usually candlelight ( Candela ,mcd) Work unit .
5、LED The luminous angle of ：-90°-+90°
6、 Spectral half width Δλ:
It represents the spectral purity of the light emitting tube .
7、 Half value angle θ1/2 And perspective ：
θ1/2 It refers to the direction in which the luminous intensity value is half of the axial intensity value and the luminous axis ( Normal direction ) The angle between .
8、 Full form ：
according to LED The angle converted from luminous solid angle , Also called plane angle .
9、 visual angle ：
finger LED The maximum angle of illumination , Depending on the perspective , Applications are also different , Also called light intensity angle .
10、 Hemiform ：
Normal direction 0° And the maximum luminous intensity value /2 The Angle between . Strictly speaking , Is the maximum luminous intensity value and the maximum luminous intensity value /2 The corresponding included angle .LED The packaging technology leads to the maximum luminous angle is not normal 0° The value of light intensity , Introduce deviation angle , It refers to the angle and normal direction corresponding to the maximum luminous intensity 0° The Angle between .
11、 Maximum forward DC current IFm：
Maximum forward DC current allowed . Exceeding this value can damage the diode .
12、 Maximum reverse voltage VRm：
The maximum reverse voltage allowed is the breakdown voltage . Beyond this value , The LED may be damaged by breakdown .
13、 The work environment topm:
The ambient temperature range in which the LED can work normally . Below or above this temperature range , The LED will not work properly , The efficiency is greatly reduced .
14、 Allowable power consumption Pm:
Allow to be added to LED The maximum value of the product of the forward DC voltage at both ends and the current flowing through it . Beyond this value ,LED fever 、 damage .