In the last blog, we looked at the basic properties and applications of SiC. In this blog, we look more closely at SiC’s durability and examine how important that durability is for its many different applications.
Silicon carbide (SiC) is a ceramic material that, for the purposes of semiconductor applications, is often grown as a single crystal. Its inherent material properties, combined with being grown as a single crystal, make it one of the most durable semiconductor materials on the market. This durability goes far beyond just its electrical performance.
SiC’s physical durability is best demonstrated by looking at some of its applications outside of electronics: it is used in sandpaper, extrusion dies, bulletproof vest plates, high-performance brake disks, and flame igniters. SiC will leave scratches on an object rather than be scratched itself. When used in high-performance brake disks, its long-term wear resistance in harsh conditions is put to the test. To be used as a bulletproof vest plate, SiC needs high physical strength, as well as good impact strength.
SiC’s use in flame igniters shows that it can also withstand extreme temperatures. When temperatures reach around 2700°C, SiC sublimates directly to the vapor phase, meaning it becomes a gas. For context, the melting point of iron is around 1500°C, so in order for a SiC component to change phase, most of the metals around it would have already melted. SiC can continue to perform at temperatures that would destroy Silicon (Si).
SiC is commonly known for its chemical inertness — it’s not attacked by even very aggressive chemicals like alkalis or molten salts, even when exposed to extreme temperatures of up to 800°C. As a result of its resistance to chemical attack, SiC is non-corrosive and can handle tough work environments that include exposure to humid air, saltwater, and a wide array of chemicals.
Because SiC has a high energy bandgap, it is extremely resistant to electromagnetic disturbances and the damaging effects of radiation. SiC can also handle higher levels of power without damage than Si.
The ability to withstand thermal shock is another key feature of SiC. Thermal shock occurs when an object is exposed to an extreme temperature gradient (i.e., when different sections of an object are at significantly different temperatures). As a result of this temperature gradient, the rate of expansion or contraction of those different sections will vary. In brittle materials, thermal shock can lead to fracture, but SiC is highly resistant to these effects. SiC’s thermal shock resistance is a combination of high thermal conductivity (350 W/m/K for a single crystal) and a low thermal expansion compared to most semiconductor materials.
SiC’s durability is one of the reasons why SiC electronics (e.g., MOSFETs and Schottky diodes) are being used for applications with aggressive environments such as HEV and EVs. Its physical, chemical, and electrical durability make it an excellent material for use in semiconductor applications requiring toughness and reliability.
