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Silicon Carbide (SiC): History and Future
Silicon carbide does occur in nature as an extremely rare mineral known as moissanite, which was first found in 1893 in Arizona’s Canyon Diablo meteor crater. However, two years previous to this, American inventor Edward G. Acheson had accidentally discovered SiC, which he named carborundum, while looking for a way to produce artificial diamonds. In the following years Acheson patented his method for making silicon carbide powder and also developed the technology that is still used today to create SiC by reducing silica with carbon at high temperatures in an electric furnace.
Thanks to the hardness of the new compound – which, until the invention of boron carbide in 1929 was the hardest known synthetic material – the late nineteenth and early twentieth centuries saw SiC very quickly became popular on an industrial scale as a highly effective abrasive, an application for which it is still used today. In more recent years SiC has also been used as the basis for long-lasting ceramics used in automotive brakes and clutches.
The first decade of the twentieth century saw SiC used as detector diodes for early crystal radio sets, which in theory makes it the first commercially important semiconductor material. At this time it was also observed that the material would glow and change colour on application of an electric current, meaning it is also an early forerunner of the light emitting diode. Later that century the material’s electrical characteristics (a high resistance up to a certain threshold voltage dropping to a much lower resistance above that threshold) saw it deployed in lightning isolators for electric power distribution systems, in which columns of SiC pellets connected between high-voltage power lines and earth ensured lightning strikes passed to earth rather than along power lines.

How Does Silicon Carbide (SiC) Compare to Gallium Nitride (GaN)?
Compared to silicon that has a band-gap of 1.12 eV (electron-volts), GaN and SiC are compound semiconductors with band-gaps that are around three times higher at 3.39 eV and 3.26 eV respectively. This means that both can support higher voltages and higher frequencies, though there are a number of differences between the two technologies that impact how they work and where they are used.
One difference between GaN and SiC is speed in terms of electron mobility – how quickly electrons can move through the semiconductor material. At 2,000 cm²/Vs, GaN’s electron mobility is 30% faster than that of silicon, while SiC has an electron mobility of 650 cm²/Vs. These differences play a part in dictating the benefits that each technology offers a target application.
The higher electron mobility of GaN, for example, makes it much more suitable for high-performance, high-frequency applications, something that is further supported thanks to a very, very small percentage of the chip being actually consumed by the gate electrode. This ensures very low capacitance meaning it is easy to achieve higher frequencies (which is why GaN semiconductors are widely used in RF devices that switch in the gigahertz range).
SiC, on the other hand, with its higher thermal-conductivity and lower-frequency operation is more suited for higher-power applications including the higher-end voltages required in EVs and data centers, some solar-power designs, rail traction, wind turbines, grid distribution and industrial and medical imaging that do not always require high-frequency switching but do need higher-voltage operation and improved heat dissipation.