What is a Semiconductor?
Engineers frequently turn to silicon carbide semiconductors for their projects — but what is silicon carbide and what makes it unique?
Semiconductors are special materials whose electrical conductivity lies somewhere between what you would see with a conductor (such as copper wire) and what you would see with an insulator (a ceramic-like glass). A semiconductor’s conductivity can be varied by adding certain additional elements, called impurities.
Silicon (Si) is an example of a pure semiconductor commonly used in electronics. Germanium (Ge) is another pure semiconductor that was used with some of the earliest electronic devices. Semiconductors are also made from compounds, including Gallium arsenide (GaAs), Gallium nitride (GaN), Silicon Germanium, (SiGe), and Silicon carbide (SiC). We’ll return to that last item in just a little bit.
Where Are Semiconductors Used?
Nearly every electronic item you encounter on a day-to-day basis contains semiconductors. They are found in everything from your smartphone or tablet, to even higher power applications such as server farms and solar arrays.
More specifically, semiconductors are a key part of the components that make up electronic systems, including ICs (integrated circuits) diodes, transistors, and MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), to name a few. These systems are among the many building blocks that make up electronic systems, and the existence of semiconductors makes all of this possible.
Silicon Carbide as a Semiconductor
Silicon is probably the most popular semiconductor in the world today, but that does not mean it’s always the best choice for electronics. One of its main competitors, silicon carbide, is at the forefront when it comes to power electronics.
Power electronics are used in just about any type of design that depends on power, whether it is converting DC solar power to AC power for your home or helping to regulate the battery power in your hybrid electric vehicle. Power electronics even come into play with the power converters you use in so many of the devices around your home.
A major element of power electronics is the bandgap, or energy gap, of the semiconductor it contains. When a semiconductor has a higher bandgap, the electronics that use it can be smaller and operate much faster and more reliably. It can also function at higher temperatures, higher voltages, and higher frequencies than other semiconductors — and that is the case with silicon carbide. While silicon has a bandgap around 1.12, silicon carbide sits at 3.26.
Power electronics — especially MOSFETs — must be able to handle extremely high voltages, referred to as the critical breakdown strength. Silicon carbide offers a significantly higher breakdown strength than silicon, meaning it can handle higher voltages in a smaller size and support higher MOSFET blocking voltages.
Thermal conductivity (which relates to how fast a semiconductor can get rid of the heat that it generates) is another important property. If a semiconductor is not effective at dissipating heat, that severely limits the operational voltages and temperature ranges semiconductor components can handle. This is another area where silicon carbide outperforms silicon: the thermal conductivity of silicon carbide is 1490 W/m-K compared to 150 W/m-K for silicon.
Silicon Carbide MOSFETs: Proven Reliability and Performance
Semiconductors have the unique property of possessing electrical conductivity somewhere between a conductor and an insulator. It is this property that makes devices such as transistors, diodes, and MOSFETs possible — and from those devices come the electronic systems we all rely on every day of our lives. While there are several different semiconductors in use today, silicon carbide offers unique solutions and key performance advantages over other commonly used materials.