Shaoxing Xinshan Science Technology Co.,Ltd
Address: Dongfangyimai, No. 2, Pujiang Road, Shaoxing, China
The high brightness LED is mainly divided into the GaAs system and AlGaAs system of infrared light, red, orange, yellow, green AlGaInP system, green and blue InGaN system, and the GaN and AlGaN system of ultraviolet light. At present, the blue light effect of the InGaN system has been high, and the red yellow light of the tetrayuan system has been widely used in lighting, backlight, display, traffic indicator and other fields. Has a broad market prospect, uv LED semiconductor uv light source in lighting, sterilization, medical, printing, biochemical detection, high density information storage and confidential communications and other fields has important application value. Infrared leds including peak wavelength from 850 nm to 940 nm infrared LED, widely used in remote control, drive, computer mouse, sensors, safety equipment and display backlighting, infrared LED demand increasing driving force mainly comes from household appliances, security system and wireless communication products, etc.
White light application is an important market for blu-ray LED chips and is also the most important development direction. It is used to form white light source by using blue - ray chip plus YAG yellow phosphor powder. At present, the international LED companies has more obvious advantages in high power blue chips, and LED chip companies at present mainly in the domestic small and medium-sized power blue chips have larger development, but because of a few years ago caused the excess production capacity, excessive investment in small and medium-sized power blue chip market appeared serious "price war". In the case of blu-ray LED chips, the main development direction is silicon LED chip, high-voltage LED chip, inverted LED chip and so on. For the small and medium power LED chip market, the current trend of the mainstream market is 0.2-0.5 W, which includes 2835, 5630 and COB packaging. For other subdivisions, such as the vertical structure of chips, the packaging can be applied to directional lighting applications, such as flashlight, lamp, flash, and spotlights.
The silicon substrate LED chip is becoming more and more concerned
At present, mainstream blu-ray chips in the market are usually grown on sapphire substrate, with Japan Japan as the representative. There is also a blu-ray chip that grows on the silicon carbide substrate and is represented by the American firm.
In recent years, the growth of blue - blue LED chips on silicon substrate has attracted more and more attention. Silicon substrate due to the automatic production line can use IC factory, are more likely to adopt the current IC factory line 6 and 8 inches of mature technology, combined with large size silicon substrate costs are relatively cheap, and the future of silicon substrate LED chip cost is expected to drop dramatically, also can promote the rapid penetration of semiconductor lighting. Silicon LED chips have the following characteristics in characteristics:
The vertical structure, using silver mirror, can make the current distribution more uniform, thus achieving the large current drive;
The silicon substrate heat dissipation is good for the chip's heat dissipation.
It is easy to carry out secondary optics with the light and uniformity of the light.
Suitable for ceramic substrate packaging;
Suitable for lighting with LED flash and strong direction, it can be used in indoor, outdoor and portable lighting market.
In the development of silicon LED chips, the chip has been widely used in digital display in 2009. Lattice lighting in June, 2012 in guangzhou has released a new generation of high power LED chip products, silicon aroused high attention of the LED industry at home and abroad, introduced including 28 mil, 45 mil mil, 35 and 55 mil, four silicon high-power LED chips, including 45 mil chip 120 lm/w lights, and at the end of the year reached 130 lm/w, and good reliability. After the ceramic packaging of silicon LED chip, it has a good cost performance compared with internationally well-known products, which has attracted great interest from both domestic and foreign sealing plants and LED lamps factories. It is reported that sharp and pry also announced that they realized the mass production of silicon substrate white optical chips by the end of 2012, and introduced two white optical chips. In addition, big plants including samsung, osram and crystal power are also actively engaged in the research of silicon LED chips.
The LED market is at a high speed, and further declines in the cost of LED chips will boost semiconductor lighting to the family. Because the silicon substrate has such advantages as low cost, IC manufacturing technology mature, with 6 to 12 inches large size silicon development of LED technology, silicon leds technology will reduce the cost and improve production efficiency has great advantages, for the LED industry will have a significant impact.
Development bottleneck for high-brightness chips
At present, the further development of the semiconductor lighting market requires the light efficiency of blu-ray LED chips to be continuously improved, and the cost will continue to decrease. At present, the LED chip based on silicon carbide has achieved the production of 200lm/w photoeffect product, and the development level of the optical effect can reach 276lm/w. In the competition of the cost reduction of LED chip and the enhancement of photoeffect, the following development bottlenecks are being encountered.
The first is the Droop effect of blu-ray. Under the condition of high current density, external quantum efficiency drops light-emitting diodes (leds), test indicated that Droop effect is caused by a variety of reasons, including auger effect, the effect of limiting the blue chips used under high current density, as a decline in the cost of hindering the lumen.
The second is Green gap and Red gap. When the wavelength goes from blue to green, the quantum efficiency of the LED drops, such as 530nm of green light quantum efficiency drops rapidly; For red light, the internal quantum efficiency can reach 100 percent in the deep red spectrum, but its efficiency drops rapidly in the case of the orange-red light wavelength (e.g., 614nm) of the ideal white light source. These effects limit the efficiency of green light and red light chips, delaying the production of high-quality white light in the future. In addition, green and yellow leds are also affected by their own polarized fields, which will become stronger with higher levels of indium atoms.
The third is the heterogeneity of epitaxy growth. Due to the defect of the crystals in the growth of epitaxial growth, large dislocation density and defects can be formed, resulting in the decrease of the light effect and the decrease of life expectancy. The blue chip of silicon carbide, sapphire, silicon substrate is heteroepitaxy, between substrate and epitaxial crystal lattice mismatch cause dislocation, at the same time due to the difference of thermal expansion coefficient in the epitaxial growth of temperature and thermal stress produces in the process, cause the epitaxial layer defect, bending crack, chip, etc. The quality of substrate directly affects the crystal quality of the epitaxial layer, thus affecting the efficiency and life span. If the GaN epitaxial homogeneous substrate, using non-polar technology, can minimize the defects of active layer, LED chip of the current density is higher than traditional chip 5 to 10 times, greatly improve the luminous efficiency. It is reported that Seoul semiconductor using homogeneous substrate nPola new product development, compared with the current LED, in the same area is five times higher than that of the brightness, but GaN homogeneous substrates for leds are still too expensive.
In general, in the future development of blu-ray LED chips, flip chip, high voltage chip, silicon chip and so on are the main trends of the future. The inverting chip can increase the injection current due to the heat dissipation, and the reliability of the product can be improved in the application process without the line. The high voltage LED chip can improve the switching efficiency of the power supply due to the better matching of the power supply voltage, and the customized IC power supply is suitable for the LED bulb lamp. Silicon-based LED chips can dramatically reduce the cost of leds because they can be extended on a 6-inch or 8-inch silicon substrate, accelerating the advent of the era of semiconductor lighting applications. For other colors, the red LED chips and green LED chip light efficiency has much room to improve, with the red light and green light LED chip is helpful to further improve, the white light is not necessarily the future in the form of a blue LED chip with yellow phosphor, may also be RGB or other forms, the future of white light encapsulation mode could happen very big change.