Chips, LED is the core component. There are many LED chip manufacturers, and then chip classification is no uniform standard, if by power category, there are high-power and medium power points; if by color, mainly red, green, blue three; if by shape Category, generally divided into the film, two kinds of discs; if by voltage classification is divided into low-voltage direct current HVDC chips and chips.
Substrate material and wafer technology as the key to growth
At present, the development of key technology is the LED chip and wafer substrate material growth techniques. In addition to the traditional sapphire, silicon (Si), silicon carbide (SiC) substrate material, zinc oxide (ZnO) and gallium nitride (GaN), etc. are also the focus of the current LED chip research. Currently, the market most of sapphire or silicon carbide substrates for epitaxial growth of a wide bandgap semiconductor gallium nitride, these two materials prices are very expensive, and are monopolized by large foreign companies, while the price of silicon carbide and sapphire substrate ratio a silicon substrate is much cheaper, can produce a larger substrate, improve the utilization of MOCVD, thereby increasing die yield. Therefore, in order to break through the barriers of international patents, research institutes and China LED companies start from the silicon substrate material.
But the problem is that high-quality combination of silicon and gallium nitride LED chips are technical difficulties, defects huge mismatch between the lattice constants and thermal expansion coefficient and high density caused by cracks and other technical problems have long hindered the chips development of.
No doubt, from the point of view of the substrate, the substrate is still the mainstream sapphire and silicon carbide, the silicon has become the future development trend of chips. For the price war in China is relatively serious, the silicon substrate is more cost and price advantage: a silicon substrate is a conductive substrate, not only can reduce the die area, can also be eliminated on the gallium nitride epitaxial layer dry etching step , combined with the hardness lower than that of silicon carbide and sapphire, the processing can also save some costs.
Most of the current LED industry 2 inches or 4-inch sapphire substrate based, such as silicon-based GaN technology can be employed, can save at least 75% of the cost of raw materials. According to the Japan Sanken Electric Company estimates that the production of large-size silicon substrate using gallium nitride blue LED low manufacturing cost than sapphire and silicon carbide substrates 90%.
Osram, the United States Puri, Japan's three leading companies such as Ken has been a breakthrough in large-size silicon substrate GaN-based LED research, Philips, Samsung, LG, Toshiba and other international LED giant also set off a silicon substrate the GaN-based LED research boom. Among them, in 2011, the United States Puri on the 8-inch silicon substrate developed a high-efficiency GaN-based LED, made luminous efficiency and device performance LED on the top level of sapphire and silicon carbide substrates comparable to 160lm / W ; in 2012, Osram successfully produced 6 inches silicon substrate GaN-based LED.