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Semiconductors are materials whose electrical conductivity at room temperature lies between that of insulators and conductors. By introducing impurities, a process known as doping, these materials can become conductors.

Currently, many semiconductor devices employ mesa device structures, which are predominantly created through two types of etching: wet etching and dry etching. While the simple and rapid wet etching plays a significant role in semiconductor device fabrication, it has inherent drawbacks such as isotropic etching and poor uniformity, which result in limited control when transferring small-sized patterns. Dry etching, however, with its high anisotropy, good uniformity, and repeatability, has become prominent in semiconductor device fabrication processes. The term “dry etching” broadly refers to any non-wet etching technology used for removing surface materials and transferring micro and nano patterns, including laser etching, plasma etching, and chemical vapor etching. The dry etching discussed in this text specifically pertains to the narrow application of processes using plasma discharge—either physical or chemical—to modify material surfaces.

Silicon Carbide (SiC) has emerged as a key material in the field of semiconductor technology, offering exceptional properties that make it highly desirable for various electronic and optoelectronic applications. The production of high-quality SiC single crystals is crucial for advancing the capabilities of devices such as power electronics, LEDs, and high-frequency devices. In this article, we delve into the significance of porous graphite in the Physical Vapor Transport (PVT) method for 4H-SiC single crystal growth.

The history of silicon carbide (SiC) dates back to 1891, when Edward Goodrich Acheson accidentally discovered it while attempting to synthesize artificial diamonds. Acheson heated a mixture of clay (aluminosilicate) and powdered coke (carbon) in an electric furnace. Instead of the expected diamonds, he obtained a bright green crystal adhering to the carbon. This crystal had a hardness second only to diamond, and was thus named carborundum. In 1904, French-Jewish chemist Henri Moissan discovered rare natural silicon carbide minerals while studying meteorite samples from the Diablo Canyon in Arizona, USA. He named these minerals moissanite, and his discovery earned him the 1906 Nobel Prize in Chemistry.

Gallium Nitride (GaN) is an important material in semiconductor technology, known for its exceptional electronic and optical properties. GaN, as a wide-bandgap semiconductor, has a bandgap energy of approximately 3.4 eV, making it ideal for high-power and high-frequency applications.

SiC substrates are the most crucial component in the silicon carbide industry, accounting for nearly 50% of its value. Without SiC substrates, it is impossible to manufacture SiC devices, making them the essential material foundation.