How SiC and GaN is impacting the EV market

When SiC MOSFETs began to be commercialised back in 2008, this marked a significant change for the power semiconductor market. It had been the first major breakthrough in the industry for decades, becoming even more evident when the technology would eventually be debuted within electric vehicles (EVs) with the launch of the Tesla Model 3.

This new generation of SiC MOSFETs offered superior power density, enhanced efficiency, and resilience to high temperatures, which directly benefited EVs by extending their range, reducing charging times, and even lowering the cost of battery electric vehicles (BEVs).

Over the past five years, the adoption of SiC MOSFETs in EV power electronics has accelerated, with Tesla and Hyundai being among the OEMs leading this charge. According to IDTechEx, SiC inverters represented 28% of the BEV market in 2023. However, another emerging technology, gallium nitride (GaN) HEMTs, is set to challenge SiC's dominance. GaN promises efficiency gains but faces hurdles, such as limited power-handling capability, which have slowed its uptake. Although there is overlap in application between SiC and GaN, both technologies are expected to secure positions in the automotive power semiconductor landscape.

Is SiC taking charge?

SiC MOSFETs are already gaining a significant amount of traction as a preferred technology within the EV space, this is despite the initial performance, reliability, and production scaling challenges. A rapid expansion in manufacturing has brought down the costs significantly, though SiC MOSFETs still remain, on average, three times more expensive than silicon IGBTs. Even so, leading OEMs like Tesla, Hyundai, and BYD have adopted the technology, and other companies, including Stellantis, Mercedes, and the Renault-Nissan-Mitsubishi alliance, have expressed intentions to follow suit.

One of the key advantages of SiC MOSFETs is their smaller size, which allows a reduction in the size of passive components, such as the inductor in a traction inverter. This results in lighter, more efficient vehicles. By switching from silicon IGBTs to SiC MOSFETs, BEV range can improve by approximately 7%, a critical factor for consumers concerned about range anxiety. Alternatively, the same range can be achieved with smaller battery capacity, lowering vehicle weight and cost.

Furthermore, as the battery capacities in EVs continue to expand, the energy savings from SiC MOSFETs become even more pronounced. Historically, these devices were reserved for high-value EVs with larger batteries. However, budget models such as the MG MG4, BYD Dolphin, and Volvo EX30, which feature battery capacities exceeding 50kWh, are paving the way for SiC MOSFETs to penetrate the mainstream passenger vehicle market in Europe and China. Tesla has already given the technology a head start in the United States with the Model 3. IDTechEx has predicted that the demand for SiC MOSFETs will increase tenfold by 2035, fuelled by their efficiency and suitability for higher voltage platforms in applications such as inverters, onboard chargers, and DC-DC converters.

Can GaN disrupt the market?

Both SiC and GaN are classified as wide bandgap (WBG) semiconductors, but GaN has an even wider bandgap than SiC, theoretically offering greater efficiency. You can read more about the differences between GaN and SiC in our article on the topic. The maximum switching frequency for silicon IGBTs is around 100kHz, which increases to 1MHz for SiC, and can reach up to 10MHz for GaN. However, this higher switching frequency introduces challenges, including electromagnetic interference (EMI), gate control issues, parasitic effects, thermal problems, and increased switching losses.

From a device-level perspective, GaN and SiC MOSFETs differ significantly. GaN is typically grown on silicon substrates, whereas SiC uses a native substrate. While silicon substrates are more cost-effective than alternatives like sapphire, they limit GaN’s potential by confining it to lateral configurations and low-voltage applications, making it unsuitable for use in high-voltage traction inverters, which are essential in EVs.

Efforts to overcome these limitations are ongoing, with innovations like vertical GaN devices and multi-level topologies showing promise for high-voltage power electronics. GaN already has a strong foothold in low-voltage auxiliary electronics used in EVs, hybrids, and internal combustion vehicles, but its future role in high-voltage EV systems remains to be fully realised.

What’s next for SiC and GaN in the EV market?

By 2035, IDTechEx projects that SiC MOSFETs will hold a market share exceeding 50% in the automotive power semiconductor sector. SiC addresses key concerns in the EV market, such as range anxiety, charging speed, sustainability, and the growing adoption of 800V architectures.

Although GaN is not yet ready for widespread adoption in high-voltage applications like traction inverters, it is expected to enter the EV power electronics market within the next five years. GaN’s initial market entry will be focused on components such as onboard chargers and DC-DC converters, with traction inverters following later. Significant advancements in substrate technology, vertical devices, and multi-level topologies are on the horizon, supported by investments from major players like ROHM, Infineon, and Renesas. These developments will likely enable GaN to become a realistic solution for EV power electronics within the coming decade.

The coexistence of silicon, SiC, and GaN technologies is anticipated in the automotive power electronics ecosystem, as each will have its strengths and optimal applications. SiC will continue to dominate in high-power applications such as inverters and onboard chargers, particularly in systems operating at 800V, while GaN is expected to carve out a role in lower-power, high-frequency applications like DC-DC converters and onboard chargers. Moreover, developments in vertical GaN technology, which aims to overcome the voltage limitations of lateral GaN devices, could bring it closer to SiC’s high-voltage capabilities, potentially making GaN a more competitive solution for EVs in the future.