According to the substrate division used for the preparation of LED upstream materials, there are three technical routes that have been industrialized, namely sapphire substrate semiconductor illumination, silicon carbide substrate semiconductor illumination, and silicon substrate semiconductor illumination. The core patents of the first two technical routes are mainly in the hands of Japan, Europe, Toyota Synthetic, Cree, Osram, Philips, etc., and the patented GaN-based LED technology on the silicon substrate is owned by China. The LED industry has broken through the important technical route of international patent blockade.
Whether it is blue-green LED or red-yellow LED, whether it is gallium or aluminum gallium indium phosphate system, whether it is sapphire, silicon carbide, silicon substrate or gallium arsenide substrate, ultra-high brightness LED chip manufacturing technology, Developed to strip substrates to prepare thin film LEDs. The reason is as follows: First, after the epitaxial film is transferred to the new substrate, it is beneficial to heat dissipation, lowering the junction temperature, improving the luminous efficiency, and prolonging the life of the device; secondly, by making a P-plane mirror and N-face roughening, the light-emitting efficiency is remarkably improved; It is beneficial to increase the working current density of the chip. Compared with other substrates, silicon substrate semiconductor illumination epitaxial materials are very suitable for the stripping substrate film transfer technology route, and silicon materials are much cheaper than silicon carbide and sapphire, and it is easy to obtain large-sized substrates, which will be obvious. Reduce the growth cost of epitaxial materials.
Of course, there are problems such as thermal mismatch and lattice mismatch between GaN and Si substrates, which are prone to cracking. It is a serious challenge to grow high quality gallium nitride based LEDs on silicon substrates. In this respect, Jingneng Optoelectronics believes that the silicon substrate LED illumination has not found a physical bottleneck, and the crack problem can be solved by means of graphics and planar substrate, and the dislocation density can reach 3-10×108cm2. Stable performance at high current densities.
GaN/Si LEDs are on the market and the outlook is promising. However, the current price of bonding gold is high, and an alternative is to be found. In fact, there are still a lot of scientific and technical problems in SSL, so both devices and epitaxial chips are both opportunities and challenges. Moreover, the advancement of SSL technology is too fast, which also brings difficulties to investors, and investment needs to be cautious.
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