What’s Down the Road for Silicon?

"A wave of new materials burst from the lab in 2017, when Tesla faced a pivotal moment in its history. The company had released two successful luxury car models, but in its effort to become a major automaker, it gambled the company’s future on making a cheaper, mass-market vehicle.

When Tesla released its Model 3, it had a secret technical edge over the competition: a material called silicon carbide. One of the key parts of an electric car is the traction inverters, which take electricity from the batteries, convert it into a different form and feed it to the motors that turn the wheels. To get the pin-you-to-your-seat acceleration that Teslas are known for, traction inverters must pump out hundreds of kilowatts, enough power to supply a small neighborhood, while being dependable enough to handle life-or-death highway use.

While previous traction inverters had been based on silicon, the Model 3’s were made from silicon carbide, or SiC, a compound that contains both silicon and carbon. STMicroelectronics, the European company that produced the silicon carbide chips Tesla used, claimed that they could increase a vehicle’s mileage range up to 10 percent while saving significant space and weight, valuable benefits in automotive design. “The Model 3 has an air-resistance factor as low as a sports car’s,” Masayoshi Yamamoto, a Nagoya University engineer who does tear-downs of electric-vehicle components, told Nikkei Asia. “Scaling down inverters enabled its streamlined design.”

The Model 3 was a hit, thanks in part to its groundbreaking power electronics, and demonstrated that electric cars could work on a large scale. (It also made Tesla one of the most valuable companies in the world.)

With Tesla’s fast rise, other automakers have moved aggressively to electrify their fleets, pushed on, in many places, by government mandates. Many of them are also planning to use silicon carbide not only in traction inverters but in other electrical components like DC/DC converters, which power components such as air conditioning, and on-board chargers that replenish the batteries when a car is plugged in at home. Silicon carbide costs much more than silicon, but many manufacturers are concluding that the benefits more than make up for the higher price.

Silicon and silicon carbide are useful in electronics because they are semiconductors: They can switch between being electrical conductors, as metals are, and insulators, as most plastics are. This ability makes semiconductors the key materials in transistors — the fundamental building blocks of modern electronics.

Silicon carbide differs from silicon in that it has a wide bandgap, meaning that it requires more energy to switch between the two states. Wide bandgap, or WBG, semiconductors are advantageous in power electronics because they can move more power more efficiently."