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Defect-free epitaxial growth occurs when one crystal lattice has nearly identical lattice constants to another. Growth happens when lattice sites of the two lattices at the interface region are approximately matched, which is possible with a small lattice mismatch (less than 0.1%). This approximate matching is achieved even with elastic strain at the interface, where each atom is slightly displaced from its original position in the boundary layer. While a small amount of strain is tolerable for thin layers and even desirable for quantum well lasers, the strain energy stored in the crystal is generally lowered by the formation of misfit dislocations, which involve a missing row of atoms in one lattice.

AlN, as third-generation semiconductor material, is not only an important blue light and ultraviolet light material, but also an important packaging, dielectric isolation and insulation material for electronic devices and integrated circuits, especially suitable for high-temperature and high-power devices. In addition, AlN and GaN have a good thermal match and chemical compatibility, AlN used as GaN epitaxial substrate, can significantly reduce the defect density in GaN devices, improve device performance.

Within the silicon carbide (SiC) industry chain, substrate suppliers hold significant leverage, primarily due to value distribution. SiC substrates account for 47% of the total value, followed by epitaxial layers at 23%, while device design and manufacturing constitute the remaining 30%. This inverted value chain stems from the high technological barriers inherent to substrate and epitaxial layer production. Three major challenges plague SiC substrate growth: stringent growth conditions, slow growth rates, and demanding crystallographic requirements. These complexities contribute to increased processing difficulty, ultimately resulting in low product yields and high costs. Furthermore, the epitaxial layer’s thickness and doping concentration are critical parameters directly impacting the final device performance.

The first generation of semiconductor materials is mainly represented by silicon (Si) and germanium (Ge), which began to rise in the 1950s. Germanium was dominant in the early days and was mainly used in low-voltage, low-frequency, medium-power transistors and photodetectors, but due to its poor high temperature resistance and radiation resistance, it was gradually replaced by silicon devices in the late 1960s. Silicon is still the main semiconductor material in the field of microelectronics due to its high technological maturity and cost advantages.

Graphite is vital in producing Silicon Carbide (SiC) semiconductors, known for their exceptional thermal and electrical properties. This makes SiC ideal for high-power, high-temperature, and high-frequency applications. In SiC semiconductor manufacturing, graphite is commonly used for crucibles, heaters, and other high-temperature processing components due to its excellent thermal conductivity, chemical stability, and resistance to thermal shock.

Chemical vapor deposition CVD refers to the introduction of two or more gaseous raw materials into a reaction chamber under vacuum and high temperature conditions, where the gaseous raw materials react with each other to form a new material, which is deposited on the wafer surface.