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Power Semiconductors

A power IC is used as a switch or rectifier in high voltage power applications.



Power semiconductors are specialized transistors and diodes that play a key role in the world’s electrical infrastructure. They start, stop, and adjust the voltage in electronic systems. What makes them different from other kinds of semiconductors is their ability to operate at higher voltages. In fact, each is marked with a “V” (voltage), along with a number, which is the maximum allowable operating voltage in a device.

These devices have been in widespread use for decades. Power MOSFETs — metaloxide semiconductor field-effect transistors — were first introduced commercially in the early 1980s, and are used today in 10- to 500-volt applications, such as power adapters and power supplies. Super-junction power MOSFETs, meanwhile, are used in 500- to 900-volt applications. And insulated-gate bipolar transistors (IGBTs), the leading midrange power semiconductor devices, are used in 1.2-kilovolt to 6.6-kilovolt applications, which is particularly important for automotive applications.

But IGBTs and MOSFETs are hitting their limits, and while they are still widely used, new wide-bandgap technologies are required. A bandgap is the energy differential between the top of the valence band and the bottom of the conduction band. The wider the bandgap, the higher the maximum voltage and temperature.

Many materials are being researched today for future power semis, including aluminum nitride, diamond, and gallium oxide. The two that are farthest along toward widespread commercialization are silicon carbide (SiC) and gallium nitride (GaN).

Silicon-based devices have a of 1.1 electron volts (eV). “That is basically the definition of how much energy it takes to rip an electron out of the bond between two silicon atoms,” explained John Palmour, former CTO of Wolfspeed. “Silicon carbide has a bandgap of 3.2 electron volts, and so it takes 3 times more energy. A lot of the characteristics of semiconductors bandgap are actually up in the exponent. We’ve got 3 times wider bandgap, but when it comes to electric breakdown, we actually have a 10 times higher electric breakdown field.”

Find the complete power semiconductor report  here (51 pages).