Silicon carbide (SiC) is a semiconductor material that has wide bandgap property which makes it ideal for high power and high temperature applications. In recent times, CVD Silicon Carbide has gained tremendous attention from power electronics sector due to its ability to operate at higher voltages, switching frequencies, and operating temperatures compared to conventional silicon. In this article, we will discuss in detail how CVD Silicon Carbide is disrupting the power electronics industry and paving way for next generation power devices.

Properties of CVD Silicon Carbide

CVD Silicon Carbide possesses some unique material properties that makes it highly suitable for power electronics:

Wide Bandgap: Silicon carbide has a bandgap of 3.26 electronvolts (eV) compared to 1.12 eV of silicon. This wide bandgap allows SiC devices to operate at higher voltages, frequencies and temperatures.

High Breakdown Electric Field: CVD Silicon Carbide has a critical electric field ten times higher than silicon. This allows SiC power devices to operate at higher voltages with thinner drift regions resulting in lower on-resistance.

High Thermal Conductivity: SiC has thermal conductivity three times higher than silicon. This excellent thermal property enables SiC devices to efficiently dissipate heat generated during switching.

Excellent Radiation Hardness: SiC is highly radiation hard and shows little degradation when exposed to radiation. This makes SiC suitable for applications in high radiation environments like space and aviation.

Improved Efficiency and Power Density

The material properties of CVD Silicon Carbide enable significant improvements in power conversion efficiency and power density:

Higher Switching Frequency: SiC switches at much higher frequencies (100 kHz vs 10-20 kHz for silicon) with low switching losses. This reduces the size of passive components.

Lower Conduction Losses: Higher critical electric field of SiC allows thinner drift region resulting in lower on-state resistance. This reduces conduction losses and improves efficiency.

Higher Operating Junction Temperature: SiC devices can operate reliably up to 150-200°C compared to 125°C of silicon. This allows more compact cooling solutions and operation with higher packing density.

These improvements in switching speed, conduction losses and temperature handling collectively allow SiC based converters to achieve power densities up to 10X higher than silicon at efficiencies exceeding 99%.

Advent of SiC MOSFETs

Initially SiC power devices were only available as Schottky diodes and bipolar junction transistors (BJTs) with limited gate control. The emergence of Silicon Carbide MOSFETs strongly kicked-off the commercial adoption of SiC:

- SiC MOSFETs provide low gate leakage, easy drive requirements and robust short circuit ruggedness.

- Major companies like Cree, Infineon, Rohm, STMicroelectronics, UnitedSiC etc are now mainstream producing and offering wide portfolio of SiC MOSFETs.

- SiC MOSFETs are now commercially available in voltages ranging from 600V to 3.3kV with continuous improvements in performance and yield.

- Automotive manufacturers are heavily evaluating SiC MOSFETs for motor control, DC-DC conversion and on-board chargers.

Realization of SiC Benefits

While SiC technology promises significant improvements, realizing its full benefits require redesigning power systems from chip level to system level. Some key ongoing developments include:

- Co-design of SiC devices and gate drivers to maximize speed while ensuring ruggedness.

- Optimized layout, circuit topology and packaging to minimize parasitics.

- New board level designs with planar bonded dies and direct bond copper substrates.

- Advanced active and passive component integration for compact modules.

- Thermal management innovations for high temperature, two-phase cooling solutions.

- New control schemes and digital controllers optimized for wide bandgap benefits.

As these efforts further mature, SiC is set to disrupt areas like EV traction inverters, solar inverters, wind turbines, DC fast chargers, UPS, and rail transportation. Countries are also investing in setting up local SiC industry to fuel this transition.

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