5 Key Advantages of Silicon Carbide

Silicon Carbide (SiC), also known as carborundum, is a compound of silicon and carbon. The material characteristics of SiC devices endow them with high breakdown voltage capabilities and low on-state resistance. These features allow for ultra-fast switching speeds and operation at high temperatures, positioning SiC as a viable successor to traditional silicon-based (Si) devices in the field of power electronics. This technology finds applications in prominent areas such as electric vehicles (EVs)/hybrid electric vehicles (HEVs) and charging, solar and energy storage systems, data and communication power supplies and uninterruptible power supplies (UPS), industrial drives, HVAC, and welding.

Schottky Barrier Diodes (SBDs) and Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) are commonly specified SiC devices. Compared to silicon devices, SiC devices exhibit five key advantages:

1. Switching Frequency and Power Density: The switching frequency of power converters impacts factors such as switch losses, transformer losses, overall converter size/weight, and electromagnetic interference (EMI). SiC MOSFETs, in contrast to silicon switches, offer low switching energy losses and ultra-low gate charge, enabling higher switching frequencies for more compact transformer designs and reduced power losses.
2. On-State Resistance (RDS(on)): RDS(on) is the resistance between the source and drain of a MOSFET. Lower on-state resistance leads to lower power losses and reduced heat generation. The RDS(on) of a 1700V SiC MOSFET is significantly lower than that of 2000V and above Si MOSFETs. This allows for the use of smaller packages with the same rated on-state resistance, enhancing the cost-effectiveness of 1700V SiC MOSFETs. SiC SBDs operate at junction temperatures (TJ) exceeding 150°C.
3. Low Switching Losses: SiC MOSFETs exhibit lower switching losses than Si MOSFETs, enhancing converter efficiency. Reduced switching losses enable smaller heatsinks or even their elimination. Lower switching losses also offer the flexibility to increase the switching frequency of auxiliary power supplies, minimizing transformer size and weight. Ultra-low switching losses and rapid switching speeds significantly improve energy efficiency.
4. Wide Bandgap: SiC devices have a wide bandgap, referring to the energy difference between the top of the valence band and the bottom of the conduction band. This extended distance allows devices to operate at higher voltages, temperatures, and frequencies. Discrete SiC Schottky diodes and SiC MOSFET devices, with a wide bandgap of 3.3eV for 4H-SiC, achieve low conduction and switching losses. When comparing SiC and Si semiconductor chips with the same structure and size, SiC chips demonstrate lower on-state resistance and higher breakdown voltage.
5. Enhanced Thermal Conductivity: SiC exhibits three times higher thermal conductivity than conventional Si. Additionally, it can withstand voltages ten times higher than ordinary silicon. Improved thermal conductivity reduces system complexity and costs. SiC MOSFET devices offer a combination of high operating voltage and fast switching speeds, a combination not typically found in traditional power transistors.

As illustrated in Figure 1, SiC devices demonstrate lower switching and conduction losses, reducing component size and increasing power density. Operating at high junction temperatures, they feature low gate resistance, low gate charge, low output capacitance, and ultra-low on-state resistance.

Available in various current ratings (6A, 8A, 10A, 16A, or 20A), SiC devices offer multiple performance advantages for power electronics system designers, including negligible reverse recovery current, high surge capability, and a maximum operating junction temperature of 175°C—making them suitable for applications demanding improved efficiency, reliability, and thermal management.

Compared to similar-rated IGBTs, SiC MOSFET devices achieve lower per-cycle switching losses and higher light-load efficiency due to their structural advantages. The inherent material properties of SiC result in SiC MOSFETs outperforming similar-rated Si MOSFETs in breakdown voltage, on-state resistance, and junction capacitance.

Supporting a maximum drain-source voltage (VDS) of 1700V, an on-state resistance (RDS(on)) of 750 mΩ, and a maximum operating junction temperature of 175ºC, SiC MOSFET devices feature simplified PCB layouts, and Kelvin source-drain connections reduce stray inductance in the gate drive circuit, improving efficiency, EMI behavior, and switching performance.