China photovoltaic cell Manufacturers, Suppliers, Factory

The basic crystal unit cell of monocrystalline silicon is the zinc blende structure, in which each silicon atom bonds chemically with four neighboring silicon atoms. This structure is also found in monocrystalline carbon diamonds.

The most basic stage of all processes is the oxidation process. The oxidation process is to place the silicon wafer in an atmosphere of oxidants such as oxygen or water vapor for high-temperature heat treatment (800~1200℃), and a chemical reaction occurs on the surface of the silicon wafer to form an oxide film (SiO2 film).

There are two types of epitaxy: homogeneous and heterogeneous. In order to produce SiC devices with specific resistance and other parameters for different applications, the substrate must meet the conditions of epitaxy before production can begin. The quality of the epitaxy affects the device's performance.

Silicon carbide (SiC) crystal growth furnaces are the cornerstone of SiC wafer production. While sharing similarities with traditional silicon crystal growth furnaces, SiC furnaces face unique challenges due to the material’s extreme growth conditions and complex defect formation mechanisms. These challenges can be broadly categorized into two areas: crystal growth and epitaxial growth.

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.

In the process of growing SiC and AlN single crystals by the physical vapor transport method (PVT), components such as the crucible, seed crystal holder and guide ring play a vital role. During the preparation process of SiC, the seed crystal is located in a relatively low temperature region, while the raw material is in a high temperature region exceeding 2400°C. The raw materials decompose at high temperatures to form SiXCy (including Si, SiC₂, Si₂C and other components).