Silicon carbide (SiC) has become one of the most critical semiconductor materials for the future of power electronics, RF/microwave devices, and wide-bandgap technologies. Among the different types of SiC substrates, N-Type SiC and Semi-Insulating (SI) SiC are the two most widely used. They share the same crystal structure, but their electrical characteristics, dopants, and end-use applications are fundamentally different.

What Is N-Type Silicon Carbide (N-Type SiC)?

N-Type SiC is a conductive silicon carbide substrate formed by doping the crystal with nitrogen (N) or phosphorus (P). These dopants introduce free electrons, turning the SiC into an n-type semiconductor with excellent electrical conductivity.

Key Characteristics of N-Type SiC

• Low resistivity: 0.02–20 Ω·cm
• Dopant: Nitrogen (most common for 4H-SiC)
• High electron mobility and carrier concentration
• Ideal for high-power, high-voltage switching devices

Where N-Type SiC Is Used

N-Type 4H-SiC is the foundation for nearly all SiC power devices, including:

• SiC MOSFETs
• SiC Schottky Barrier Diodes (SBDs)
• SiC JFETs & IGBTs
• Power modules for EVs and energy storage
• High-voltage rectifiers and converters

Because of its conductive nature, N-Type SiC is designed specifically for power electronics, where precise control of current conduction is required.

What Is Semi-Insulating SiC (SI SiC)?

Semi-insulating SiC is engineered to have extremely high resistivity, typically in the range of 10⁶–10⁹ Ω·cm. This is achieved through vanadium (V) doping or by growing ultra-high-purity intrinsic SiC.

Vanadium traps free carriers, preventing electrical conduction while preserving the excellent thermal and mechanical properties of SiC.

Key Characteristics of Semi-Insulating SiC

• Very high resistivity: 1–10⁹ Ω·cm
• Dopant: Vanadium (V)
• No free carriers → behaves like an insulator
• Excellent RF performance with low leakage and low parasitic capacitance

Where SI SiC Is Used

Semi-insulating SiC is essential for RF and microwave devices, such as:

• GaN-on-SiC HEMTs (5G base stations)
• Radar and satellite communication systems
• Low-noise amplifiers (LNA)
• High-frequency power amplifiers
• RF front-end modules

SI-SiC acts as the ideal substrate for GaN epitaxy because it provides electrical isolation, low dielectric loss, and exceptional thermal conductivity.

N-Type vs. Semi-Insulating SiC: What’s the Real Difference?

Below is a detailed comparison of the two material types.

1. Resistivity

• N-Type: Low resistivity (conductive)
• SI SiC: Ultra-high resistivity (insulating)

2. Function in Devices

• N-Type: Current conduction in power devices
• SI SiC: Electrical isolation for RF and GaN-based devices

3. Doping Difference

• N-Type: Nitrogen or phosphorus
• SI SiC: Vanadium (carrier compensation)

4. Thermal Properties

Both maintain SiC’s inherent high thermal conductivity, but SI SiC is preferred for RF heat dissipation under extremely high frequencies.

5. Cost

• N-Type: Lower cost; widely produced
• SI SiC: Higher cost; requires high-purity growth and vanadium compensation

6. Best Applications

Why Choosing the Correct SiC Substrate Matters

The substrate determines:

• Device performance
• Leakage current
• Switching speed
• Thermal stability
• RF noise and signal purity
• Overall efficiency

Power electronics demand conductive substrates (N-Type), while RF and microwave technologies require insulating substrates (SI SiC).

Selecting the correct SiC type ensures better performance, longer device lifetime, and lower energy loss.

Conclusion

Both N-Type SiC and Semi-Insulating SiC are essential materials that drive modern electronics.

• If your application involves power conversion, energy storage, EVs, or industrial drives, choose N-Type SiC.
• If you work with 5G RF, microwave, radar, or GaN-based systems, SI SiC is the correct choice.

Understanding these differences helps engineers and buyers select the right substrate for optimal performance.