The Transition from Si to SiC in Power Electronics

• It is a wide bandgap material, making the leakage current lower at high temperatures.
• Has a higher thermal conductivity that helps it support high-current density applications.
• Has a lower energy loss, helping it to minimize power losses.
• Has a higher switching frequency, which reduces bulky large periphery components.
• Has lower switching losses due to its smaller die size and reduced parasitic capacitances, allowing the power converters to operate at higher switching frequencies and speeds.
• Offers higher temperature operation, helping reduce large mechanical heat sinks. So, we can now see how the SiC device has many advantages over its Si counterpart. This is why many applications are moving from Si to using SiC.

Understanding the Electro-thermal Advantages

In power electronics, providing high power levels in a very efficient way while minimizing power loss is important. Meeting extreme thermal requirements is also very important. SiC offers these and low drain-to-source R_DS(ON) 300 to 400 times lower than Si devices. This figure-of-merit (FOM) provides technology manufacturers with a desirable feature for designing efficient power electronics equipment. Additionally, SiC can manage higher power levels than Si in the same active die area – allowing for devices with the same performance level in a reduced dimension.

Moreover, SiC offers high electro-thermal conductivity and fast switching. It also has low output capacitance and R_DS(ON). Because it can handle high energy levels and with much higher switching frequencies, it enables significant system cost savings for manufacturers. Why? Because these FOMs translate to the downsizing of magnetic parts like transformers, chokes and inductors used in all switching mode designs. All these FOMs make it well suited for switching designs in applications like three-phase inverters, digital power supplies and electronic (AC/DC and DC/DC) converters.

One of the FOMs that manufacturers seek today is efficiency. This is a major drive in many applications due to a global push for ‘green’ energy initiatives. As shown below, Figure 1 displays how more efficient SiC is over Si. Making it a go-to technology in many of today’s next-generation designs.

Figure 1: Comparison between Si and SiC.

Wide bandgap semiconductor technologies like SiC are ideal for next-generation efficient power electronics. (See Figure 2) SiC offers excellent voltage-blocking capabilities starting at 650 V and provides even greater benefits at higher voltages. One key initiative in next-generation solutions is “green” systems (i.e., energy-efficient). SiC provides this capability – its wide bandgap ability allows for greater power efficiency, smaller size, lighter weight and lower overall cost – equating to “greener” solutions.

Figure 2: Table comparing Si and SiC parameters.

Some Final Takeaways

We now have a better understanding of how Si compares to SiC. Both have a place in our new digital world in many applications. But in many solutions, SiC has clearly excelled. SiC technology can be used in a wide range of power electronic solutions. Using SiC in applications like high-frequency DC/DC and AC/DC offers many benefits due to the wide operating gate drive range. Additionally, using SiCs in electric vehicle inverters, one can achieve low conduction losses and robust short-circuit handling.

Further, evolutionary SiC achievements will catapult this technology into more applications – while opening others. Moreover, progress in package design, market acceptance and fast-growing markets will push SiC further into even more solutions.

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