Wide Band Gap—The Revolution In Power Semiconductors

New government regulations and industry standards are leading companies to adopt wide bandgap (WBG) power solutions, both to reduce their carbon footprint and to meet increasing demand for higher power systems aimed at electric vehicles, renewable energy, datacenters, and other markets.

The automotive industry is one of the biggest markets driving demand for WBG power devices. The European Union has set tough emission reduction targets,1 ordering carmakers to achieve 98 grams or less of CO2 per kilometer by 2020 for vehicle fleets. To achieve this level, automakers need to offer a mixed portfolio of hybrid and electric vehicles. In 2017, 73 million passenger cars were produced worldwide. While only about 4 million of those were EVs and hybrids, the number is expected to grow significantly (figure 1).

A typical electric vehicle contains $500 of semiconductor content now. However as Advanced Driver Assistance Systems (ADAS) progress, the industry will see increased demand in communications, telemetry, and infotainment, requiring over a kilowatt more of power.

With more onboard sensors and more data transmitted between vehicles and the cloud, it is expected that about 4,000 GB of data will be transmitted per day for each car. That will require over 400 hyper scale datacenters, just for the automotive industry.

Wide Band Gap Materials
As new systems push for increased power densities and higher efficiencies, silicon technology simply is not efficient enough, and WBG materials need to be introduced that can offer higher performance.

Silicon carbide (SiC) and gallium nitride (GaN) are compound materials that have existed for over 20 years, starting in the military and defense sectors. They are very strong materials compared to silicon and require three times the energy to allow an electron to start to move freely in the material. This larger energy gap (or wider band gap) gives these materials superior qualities, such as faster switching, higher efficiency, and increased power density (figure 2).

One of the main advantages in WBG power transistors is the dramatic reduction of switching losses. Think of a switch turning on and off. It takes a certain amount of time to get from the ON state to the OFF state. During this transition time, power is wasted. The goal is for the device is to switch as quickly as possible to reduce power loss and increase the efficiency of the transistor.

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