LED chip technology and analysis of domestic and international differences

    At present, the key to the development of LED chip technology lies in substrate materials and wafer growth technology. In addition to traditional sapphire, silicon (Si), and silicon carbide (SiC) substrate materials, zinc oxide (ZnO) and gallium nitride (GaN) are also the focus of current LED chip research. At present, sapphire or silicon carbide substrates are mostly used in the market for epitaxial growth of broadband gap semiconductor gallium nitride. These two materials are both very expensive and monopolized by foreign large enterprises. The price of silicon substrates is much cheaper than that of sapphire and silicon carbide substrates, and larger substrates can be made to improve the utilization rate of MOCVD and thus improve the yield of the tube core. So, in order to break through international patent barriers, Chinese research institutions and LED companies are starting to research silicon substrate materials.

    But the problem is that the high-quality combination of silicon and gallium nitride is a technical challenge for LED chips. The huge mismatch between the lattice constants and thermal expansion coefficients of the two has long hindered the development of the chip field, resulting in high defect density and cracks.

    Undoubtedly, from a substrate perspective, the mainstream substrates are still sapphire and silicon carbide, but silicon has become the future development trend in the chip field. For China, which has a relatively severe price war, silicon substrates have more cost and price advantages: silicon substrates are conductive substrates, which can not only reduce the area of the tube core, but also save the dry corrosion step of the gallium nitride epitaxial layer. In addition, the hardness of silicon is lower than that of sapphire and silicon carbide, which can also save some costs in processing.

    At present, the LED industry mainly relies on 2-inch or 4-inch sapphire substrates. If silicon based gallium nitride technology can be used, at least 75% of raw material costs can be saved. According to the estimation of Sanken Electric Company in Japan, the manufacturing cost of using silicon substrates to produce large-sized blue gallium nitride LEDs will be 90% lower than that of sapphire and silicon carbide substrates.