on October 10th 6,013

Silicon Carbide (SiC): Properties, Production, Advantages and Applications

This article explores Silicon Carbide (SiC) properties, crystal structure, and various production methods, including the Acheson process, PVT, CVD, and PDC techniques. It examines the advantages and disadvantages of SiC-based devices, compares SiC with Gallium Nitride (GaN), and highlights its diverse applications across manufacturing, defense, energy, aerospace, telecommunications, and lighting systems.

Catalog

Figure 1. Silicon Carbide

What is Silicon Carbide (SiC)?

Silicon Carbide, or SiC, is a semiconductor made from silicon and carbon atoms. Unlike standard silicon, it has a wide bandgap of about 3.26 eV. This property allows it to perform efficiently when exposed to high voltages, high frequencies, and high temperatures.

Because of its wide bandgap, SiC has very few natural charge carriers, meaning it can handle heavy electrical loads without overheating or breaking down. This makes it ideal for power electronics used in electric vehicles, renewable energy converters, and industrial systems that operate under harsh thermal or electrical conditions.

Properties of Silicon Carbide

Property	Min (SI)	Max (SI)	Units (SI)	Min (Imperial)	Max (Imperial)	Units (Imperial)
Density	3.1	3.22	g/cm³	193.4	201.1	lb/ft³
Atomic Volume (avg.)	0.01	0.0105	m³/kmol	610	641	in³/kmol
Bulk Modulus	180	250	GPa	26.1×10⁶	36.3×10⁶	psi
Shear Modulus	160	200	GPa	23.2×10⁶	29.0×10⁶	psi
Young’s Modulus	410	450	GPa	59.5×10⁶	65.3×10⁶	psi
Poisson’s Ratio	0.14	0.19	—	0.14	0.19	—
Compressive Strength	3,000	4,000	MPa	435	580	ksi
Tensile Strength	200	400	MPa	29	58	ksi
Modulus of Rupture (Flexural)	350	550	MPa	51	80	ksi
Fracture Toughness (K_IC)	2	5	MPa·m¹ᐟ²	1.8	4.5	ksi·in¹ᐟ²
Hardness (Vickers)	22	30	GPa	3.19×10⁶	4.35×10⁶	psi
Specific Heat	670	800	J/kg·K	0.16	0.19	BTU/lb·°F
Thermal Conductivity	90	120	W/m·K	52	69	BTU·in/h·ft²·°F
Thermal Expansion Coefficient	3.7	4.2	×10⁻⁶/K	2.06	2.33	×10⁻⁶/°F
Maximum Service Temperature (Air)	—	1873	K	—	2920	°F
Melting / Decomposition Point	—	3000	K	—	4940	°F
Electrical Resistivity (intrinsic)	10³	10⁹	Ω·cm	10³	10⁹	Ω·cm
Electrical Resistivity (doped power SiC)	0.01	10	Ω·cm	0.01	10	Ω·cm
Dielectric Constant (1 MHz)	9.7	9.7	—	9.7	9.7	—
Dielectric Breakdown Strength	2.5	3	MV/cm	6.35×10⁶	7.62×10⁶	V/mil

Structure of Silicon Carbide

Figure 2. Structure of Silicon Carbide (SiC)

The structure of silicon carbide consists of a network of tetrahedra, as shown in the figure, where each silicon atom is bonded to four carbon atoms through strong covalent Si–C bonds. These bonds form a tetrahedral arrangement with equal bond lengths and angles, creating a tightly packed and stable framework. When repeated throughout the crystal, these tetrahedra interconnect to form a layered, polar lattice. This structural arrangement gives SiC its high hardness, thermal stability, and ability to maintain integrity under extreme conditions.

How Silicon Carbide is Produced?

SiC can be produced using several manufacturing methods, depending on the desired purity, crystal form, and end use.

Acheson (Carbothermic) Process

The Acheson process, shown in the figure below, is the most common and traditional method used to produce silicon carbide (SiC). In this process, a mixture of silica (SiO₂) and carbon is packed around a graphite core within an electric furnace. When heated to very high temperatures, the reaction zone near the core forms SiC crystals, while byproducts such as carbon monoxide and metal oxides accumulate in surrounding layers. This setup allows for large-scale and cost-effective production, though the resulting SiC may contain impurities and less uniform crystal structures.

Figure 3. Acheson (Carbothermic) Process

Sublimation / Physical Vapor Transport (PVT or Lely Process)

The figure below illustrates the PVT (Lely) process, a technique used to grow large, high-quality single-crystal SiC wafers for semiconductor applications. In this method, polycrystalline SiC powder at the bottom of the graphite crucible is heated until it sublimates into vapor, which then re-condenses onto a cooler SiC seed crystal at the top, forming a pure monocrystalline layer. As shown, the setup with controlled heating, an inert argon atmosphere, and precise temperature gradients, enables excellent crystal uniformity, though it demands energy and time.

Figure 4. PVT (Lely) Process

Chemical Vapor Deposition (CVD)

The CVD process involves introducing gaseous precursors containing silicon and carbon into a heated reaction chamber, where they undergo gas-phase reactions and deposit a thin SiC film onto a substrate. The diagram below, illustrates key steps such as diffusion, surface adsorption, and film growth, all driven by controlled energy input. This method enables precise control over film thickness, purity, and crystal quality, making it ideal for advanced electronic applications, though it requires complex and costly equipment.

Figure 5. Chemical Vapor Deposition (CVD)

Polymer-Derived Ceramics (PDCs)

The PDC process begins with a polymer precursor that contains silicon and carbon elements. When this polymer is heated under controlled conditions, it converts into a ceramic form of SiC. This method allows to mold complex shapes, fibers, or composites before the final conversion step. While flexible and adaptable, the resulting ceramics may have slight structural imperfections and lower purity compared to other methods.

Advantages and Disadvantages

Advantages

• Operates efficiently at high voltages and temperatures.

• Reduces switching losses, improving overall system efficiency.

• Conducts heat effectively, minimizing the need for large cooling systems.

• Supports higher switching frequencies, enabling smaller circuit components.

• Allows compact, lightweight designs suited for electric vehicles, renewable energy converters, and industrial power systems.

Disadvantages

• More expensive to produce than silicon.

• Manufacturing is complex, with lower yields per wafer.

• Requires specialized tools and precise fabrication conditions.

• Demands careful circuit and gate-drive design to operate safely.

• The supply chain and industry infrastructure are still developing compared to silicon.

Silicon Carbide (SiC) vs. Gallium Nitride (GaN)

Figure 6. Gallium Nitride and Silicon Carbide

Parameter	Silicon Carbide (SiC)	Gallium Nitride (GaN)
Bandgap Energy	Has a wide bandgap of about 3.2 eV, allowing strong operation under heat and voltage.	Slightly wider at around 3.4 eV, giving very fast switching ability.
Breakdown Voltage	Can handle very high voltages above 1,000 volts, ideal for heavy-duty systems.	Works best below 650 volts, suited for lower-voltage circuits.
Switching Speed	Switches quickly, improving efficiency in power conversion.	Switches even faster, excellent for high-frequency electronics.
Thermal Conductivity	Conducts heat very well, helping devices stay cool during operation.	Transfers heat less effectively, so it needs better cooling design.
Power Efficiency	Highly efficient when running high-power or high-voltage loads.	Extremely efficient at low voltages and high frequencies.
Operating Temperature	Performs reliably up to about 200 °C, ideal for harsh environments.	Works well up to about 150 °C, better for compact and cooler devices.
Material Strength	Very hard and durable, with excellent mechanical stability.	More fragile and sensitive to processing conditions.
Common Uses	Found in electric vehicles, solar inverters, and industrial power converters.	Used in fast chargers, wireless systems, and radio-frequency devices.
Advantage	Best for high-power, high-temperature, and high-voltage operations.	Best for compact, high-speed, and high-frequency applications.

Applications of Silicon Carbide

Manufacturing

In manufacturing, SiC is widely used to produce abrasive tools, grinding wheels, and cutting discs. Its exceptional hardness allows these tools to maintain their shape and cutting ability even after long periods of heavy use. Because of this durability, SiC-based tools are ideal for machining metals, ceramics, and composite materials.

Defense

SiC serves as a lightweight yet extremely strong material for ballistic armor plates and vehicle protection systems. It absorbs and disperses impact energy efficiently, improving safety while reducing overall equipment weight. Additionally, it is used in missile components and defense coatings that must endure high heat and stress.

Energy

In the energy sector, SiC plays a major role in solar inverters, wind turbine converters, and power control modules for renewable energy systems. Its ability to operate efficiently at high voltages helps reduce power losses and improve energy conversion. This makes SiC important for building cleaner and more reliable power grids.

Aerospace

SiC components are found in aircraft engines, satellites, and thermal protection systems. They perform reliably in environments with extreme heat, pressure, and radiation. Because of its stability and lightweight nature, SiC helps improve fuel efficiency and durability in aerospace designs.

Telecommunications

SiC materials are used in radio frequency (RF) amplifiers, base stations, and 5G communication systems. Their fast switching and heat resistance allow reliable operation at very high frequencies. This leads to stronger signals, reduced energy use, and longer equipment life.

LED and Lighting Systems

SiC acts as a strong and thermally stable substrate for LED production. It enhances brightness and efficiency while allowing LEDs to operate at higher temperatures without degradation. This results in longer-lasting lighting systems used in homes, vehicles, and streetlights.

Conclusion

Silicon Carbide stands out for its unique combination of thermal stability, mechanical strength, and electrical efficiency. Its wide bandgap enables reliable operation in extreme conditions, making it ideal for power electronics and advanced industrial systems. While production costs and fabrication complexities remain challenges, SiC’s superior performance offers clear benefits over conventional silicon and even GaN in certain domains. Its broad application in industries show its growing role in next-generation technologies.