1 Introduction As a new wide bandgap semiconductor material, GaN has been a hot spot in the field of compound semiconductors in the world. GaN is a direct bandgap material, which can form a continuously variable ternary or quaternary solid solution alloy (AlGaN, InGaN, AlInGaN) with InN and AlN. The corresponding wavelength covers the range of red to near-ultraviolet light, and has It has excellent properties such as chemical stability and thermal stability, so it has great application prospects in the field of optoelectronics. Secondly, compared with other materials such as Si and GaAs, GaN materials have higher electron mobility at high electric field strength, which makes them have high application value in microelectronic devices. In the past ten years, the wide bandgap semiconductor materials and devices represented by GaN have developed rapidly, which has greatly promoted the development and application of information science and technology. It is called the first generation semiconductor represented by Si and GaAs. A third-generation semiconductor after the second generation of semiconductors. From the first GaN LED reported by Pankove in 1971 to the GaN-based blue laser developed by Nakamura, it only took only twenty years. In recent years, the research and development of GaN-based materials and devices has been greatly accelerated. Due to the extremely difficult growth of GaN large-sized bulk single crystals, all mature devices are now based on sapphire or SiC hetero-substrate. However, from the perspective of lattice matching, conductance and thermal conductivity, sapphire is not an ideal heteroepitaxial substrate, and although the lattice mismatch between SiC substrate and GaN is smaller than that of sapphire substrate, it is difficult to process and expensive. The price also limits the further application development of the substrate. Compared with the above two substrates, the Si substrate has advantages other than lattice mismatch and thermal mismatch, and other aspects are in line with the requirements of GaN material growth, such as low cost, large size, high quality, and electrical conductivity. The development of GaN-based materials and devices on Si substrates will further promote the integration of GaN-based devices with traditional Si-based devices and is considered to be the most promising GaN substrate material. However, since people have paid considerable attention to finding substrates with small lattice mismatches, the use of Si substrates has not caused much interest. With many technological and conceptual breakthroughs, Si substrates The growth of GaN-based materials has increasingly become the focus of attention. China's Nanchang University first broke through the silicon-based GaN LED epitaxial wafer and the new substrate solder stripping technology, using the LP-MOCVD system to successfully grow high-quality InGaNMQW blue LED epitaxial wafer on the Si (111) substrate, X-ray twin crystal The full width at half maximum of symmetric and asymmetric rocking curves has reached the level of GaN LEDs on the sapphire substrate. 2. Epitaxial growth technology Epitaxial techniques for achieving GaN-based material growth include metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and hydride vapor phase epitaxy (HVPE). 2.1 MOCVD MOCVD is a non-equilibrium growth technique that relies on a source gas transport process and subsequent thermal cracking of a Group III alkyl compound with a Group V hydride. Both composition and growth rate are determined by the flow of various components and the precisely controlled source flow. An important feature of MOCVD is that the temperature of the reaction tube wall is much lower than the temperature of the internally heated substrate, resulting in a reduction in heat pipe wall reaction consumption. The MOCVD method has a moderate growth rate and can control the film thickness relatively accurately. It is especially suitable for large-scale industrial production of LEDs and LDs. It has become the most used method for growing materials and devices. EMCORE in the United States, AIXTRON in Germany, and Thomas Swan in the United Kingdom have developed Group III nitride MOCVD (LP-MOCVD) equipment for industrial production.