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In traditional silicon power device fabrication, high-temperature diffusion and ion implantation stand as the primary methods for dopant control, each with its advantages and disadvantages. Typically, high-temperature diffusion is characterized by its simplicity, cost-effectiveness, isotropic dopant distribution profiles, and lower introduction of lattice damage. Conversely, ion implantation, though complex and costly, enables precise independent control over dopant concentration and depth but introduces a significant number of point defects and extended defects into the substrate.

In the semiconductor industry, epitaxial layers play a crucial role by forming specific single-crystal thin films atop a wafer substrate, collectively known as epitaxial wafers. Particularly, silicon carbide (SiC) epitaxial layers grown on conductive SiC substrates produce homogenous SiC epitaxial wafers, which are instrumental in the fabrication of power devices such as Schottky diodes, MOSFETs, and IGBTs, with 4H-SiC substrates being the most widely utilized.

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.

Quartz (SiO₂) material is very similar to glass at first glance, but the special thing is that the general glass is made up of many components (such as quartz sand, borax, boric acid, barite, barium carbonate, limestone, feldspar, soda ash, etc.), while the quartz contains only SiO₂ components, and the microstructure of its silicon dioxide tetrahedral structural units composed of a simple network.

The degree of graphitization is an essential measure used to assess how close carbon atoms are to forming a tightly-packed hexagonal graphite crystal structure.

We know that further epitaxial layers need to be built on top of some wafer substrates for device fabrication, typically LED light-emitting devices, which require GaAs epitaxial layers on top of silicon substrates; SiC epitaxial layers are grown on top of conductive SiC substrates for building devices such as SBDs, MOSFETs, etc. for high voltage, high current and other power applications; GaN epitaxial layers are built on top of semi-insulating SiC substrates for building HEMTs and other RF applications.