SiC

Silicon carbide (SiC) is a compound of silicon and carbon forming a covalent network solid. It has a wide bandgap, typically 2.3 to 3.3 eV depending on polytype, which allows operation at high temperatures and voltages and enables blue-green optoelectronic applications. SiC occurs in many crystalline forms called polytypes; the most common are cubic 3C-SiC and hexagonal 4H-SiC and 6H-SiC, each differing in stacking sequence but sharing the same chemical formula. The material is exceptionally hard (Mohs 9–9.5), has high thermal conductivity, and a very high melting point around 2700 C, alongside chemical inertness and high breakdown field.

Natural occurrence and production: In nature, silicon carbide is known as moissanite, but it is extremely rare. Large-scale use depends on synthetic production. The original industrial method was the Acheson process, where silica and carbon are fused in an electric furnace to produce SiC and silicon monoxide. Modern production employs carbothermic reduction, chemical vapor deposition (CVD) for thin films, and bulk crystal growth by methods such as physical vapor transport (PVT) or the Lely process to obtain large single crystals used as substrates.

Applications: SiC is widely used as an abrasive and in high-performance cutting tools and refractories. In electronics, its wide bandgap and high breakdown field enable efficient high-temperature, high-voltage devices such as diodes and MOSFETs, with applications in power conversion and electric vehicles. It is also used as a substrate for GaN-based optoelectronics and in high-temperature electronics, sensors, and harsh-environment components. Doping with nitrogen yields n-type material; p-type doping is achieved with aluminum or boron.