Silicon (Si) has long been the key semiconductor material in most electronic applications, but when compared to SiC, it appears less efficient. SiC is now being adopted in a variety of applications, particularly in electric vehicles, to address the energy and cost challenges associated with developing high-efficiency, high-power devices.

SiC, which is composed of pure silicon and carbon, has three major advantages over silicon:

Higher Critical Avalanche Breakdown Field Strength
SiC can withstand an electric field that is eight times stronger than silicon before experiencing avalanche breakdown. This allows SiC devices to operate at much higher voltages compared to silicon devices, providing stronger power transmission capabilities.

Greater Thermal Conductivity
SiC has a higher thermal conductivity than silicon, meaning it can dissipate heat more effectively. This enables SiC devices to operate at higher power densities and higher temperatures while maintaining performance, making them more efficient in high-power and high-temperature environments.

Wider Bandgap
SiC has a bandgap of 3 electron volts (eV), which is significantly wider than the 1.1 eV bandgap of silicon. This wide bandgap allows SiC to operate at higher temperatures with lower leakage currents, improving efficiency and reliability. The wider the bandgap, the less leakage current and power loss there will be, enhancing overall performance.

In summary, the unique properties of SiC, such as its high breakdown strength, excellent thermal conductivity, and wide bandgap, make it an ideal material for modern high-power, high-efficiency applications like electric vehicles, power electronics, and energy conversion systems.

SiC substrates have higher electric field strength, allowing for the use of thinner base structures, which can be as thin as one-tenth of a silicon epitaxial layer. Additionally, the doping concentration of SiC is twice that of silicon, which reduces the surface resistance of devices and significantly decreases conduction losses. SiC is now widely recognized as a reliable alternative to silicon technology. Many power module and inverter manufacturers have already planned to incorporate SiC technology in their future product roadmaps. This wide bandgap technology significantly reduces switching and conduction losses under specific loads, improves heat dissipation management, and provides unprecedented energy efficiency.

In power electronic systems, thermal design is critical as it ensures high energy density while minimizing circuit size. In these applications, SiC, with its thermal conductivity three times that of silicon semiconductors, has become the ideal semiconductor material. SiC technology is suitable for high-power projects such as motors, drives, and inverters. Electric drive manufacturers are developing new drive circuits to meet the converter’s demand for higher switching frequencies and are using more complex, clever topologies to reduce electromagnetic interference (EMI).

SiC devices require fewer external components, leading to more reliable system layouts and lower manufacturing costs. With higher efficiency, smaller form factors, and lighter weight, the cooling requirements of intelligently designed systems are also reduced.

Several automakers have introduced hybrid and electric vehicles with new power concepts, becoming pioneers in the market. These vehicles include new devices and systems, such as inverters providing power to the engine (up to 300kW), onboard battery chargers ranging from 3.6kW to 22kW, 3.6kW to 22kW inductive chargers (wireless charging), DC/DC converters up to 5kW, and inverters for auxiliary loads like air conditioning and power steering systems.

One of the main barriers to the development of hybrid and electric vehicles is the high-voltage battery. By utilizing SiC, automakers can reduce the size of the battery while lowering the overall cost of electric vehicles.

Additionally, due to SiC’s excellent thermal management properties, manufacturers can also reduce the cost of cooling powertrain components. This helps reduce the weight and cost of electric vehicles.

Electric vehicles are one of the main driving forces behind the adoption of silicon carbide (SiC), and are expected to account for approximately 60% of the total SiC market capacity. SiC devices, used in the main drive, onboard chargers (OBC), and DC-DC converters, significantly improve efficiency, thereby enhancing the driving range of electric vehicles. Based on these advantages, almost all manufacturers of main drive inverters are focusing on researching SiC-based solutions for their main drive inverters.

On-board chargers (OBC) contain various power conversion devices, such as diodes and MOSFETs. The goal is to reduce the size of power electronic circuits by using small passive components, thereby integrating them all together. If the semiconductor devices used can be controlled at high switching frequencies within the same circuit, this goal can be achieved. However, due to the poor thermal performance of silicon, high switching frequency solutions are not suitable. SiC MOSFETs provide an ideal solution for such applications. Currently, the majority of OBC and DC-DC manufacturers use silicon carbide devices as efficient, high-voltage, and high-frequency power components.

5G power supplies and switch-mode power supplies (SMPS) represent the second strategic market for silicon carbide. The traditional switch-mode power supply market, such as Boost and high-voltage power supplies, has always had high power density requirements. From the early Gold and Silver standard telecom power supplies to today's 5G telecom power supplies and cloud data center power supplies, all of these have stringent energy efficiency demands.

"Silicon carbide devices have no reverse recovery, which makes power supply efficiency very high, reaching up to 98%. Power supplies and 5G power supplies represent the most traditional and currently relatively large market for silicon carbide devices.”

Electric vehicle (EV) charging stations are also one of our strategic markets for silicon carbide. There are many solutions for charging stations, but currently, the most popular among consumers is DC fast charging.

DC fast chargers require very high charging power and efficiency, which can only be achieved through high voltage. In the application of EV charging stations, silicon carbide is widely used in both Boost converters and output diodes. Many EV charging station solutions now incorporate silicon carbide MOSFETs as the main switches, and their application prospects are very promising.

In the field of solar inverters, the usage of silicon carbide diodes is also very significant. The installation of solar inverters continues to grow every year, and it is expected that in the next 10 to 15 years, 15% of energy (currently 1%) will come from solar power. Solar energy is free and inexhaustible. Relevant policies have already been introduced domestically, allowing individuals to sell solar electricity to the national grid.

"Silicon carbide semiconductors can be used in the Boost converters of solar inverters. With the optimization of solar inverter costs, many manufacturers will use SiC MOSFETs as the main inverter devices to replace the original three-level (inverter) complex control circuits.”

"In terms of policy drivers, the EU has set the 20-20-20 targets, meaning by 2020, energy efficiency should increase by 20%, CO2 emissions should be reduced by 20%, and renewable energy should account for 20%. The NEA has also set clean energy goals, aiming to meet 20% of China’s energy demand by 2030."

Conclusion

Long-term reliability has become a hallmark of SiC MOSFETs. The next task for power semiconductor manufacturers is to develop multi-chip power modules or hybrid modules that integrate traditional silicon transistors and SiC diodes into the same physical device. Due to their higher breakdown voltage, these modules can operate at higher temperatures. They also provide high efficiency while further reducing device size.

From the current market prices, SiC MOSFETs have system-level advantages compared to silicon IGBTs. Moreover, as 150mm wafer manufacturing becomes widely adopted, the price of SiC MOSFETs is expected to continue to decrease. Some manufacturers have already begun producing 200mm (8-inch) wafers. With the increase in wafer size, the cost per die will decrease, although the yield may also decrease. Therefore, manufacturers must continuously improve their processes.

However, due to the higher manufacturing cost of SiC devices and the lack of mass production, widespread adoption remains a challenge. Bulk production of SiC devices requires a carefully designed robust architecture and manufacturing processes, such as testing devices with smaller sizes and operating in higher current and voltage ranges during wafer testing.

Once these challenges are overcome, OEM designers will adopt more SiC devices, fully leveraging their excellent electrical characteristics, significantly reducing system costs, and improving overall efficiency.