Silicon carbide (SiC) is widely used in power electronics, RF devices, and photonics research thanks to its excellent thermal conductivity, high breakdown electric field, and superior optical properties. However, the selection criteria for SiC substrates differ depending on the application. This article provides key points and examples to guide you through the selection process.
 

一、Key Factors in Selecting SiC Substrates

1. Conductivity Type

n-type / p-type conductive SiC Substrates: Suitable for power devices such as MOSFETs and diodes.
Semi-insulating SiC Substrates: Used in RF and microwave applications.
High-purity undoped SiC Substrates: Preferred for optics and photonics research.
 

2. Polytype and Orientation

 
Polytypes: 4H-SiC (industry standard with high electron mobility), 6H-SiC (used in some research), 3C-SiC (still in research stage).
Orientation: (0001), (11-20), etc. Orientation affects epitaxial growth and device performance. 

3. Size and Thickness

 
Common diameters: 2", 3", 4" (research-grade), 6" (industrial).
Thickness: typically 300–500 µm, depending on process requirements.
 

4. Surface Quality

 
Polishing: Single-side polished (SP) or double-side polished (DSP).
Defect control: micropipes, dislocations, scratches, roughness.
 

5. Optical and Electrical Parameters

 
Resistivity range (critical for semi-insulating SiC substrates).
Optical transmittance and refractive index (important for photonics).
 

二、Selection Examples

Example 1: For Power Electronics
Application: MOSFETs, Schottky diodes (SBDs)
 
Recommended parameters:
Conductivity: n-type
Polytype: 4H-SiC
Size: 4", thickness ~350 µm
Orientation: (0001)
Surface: SP, defect density < 500 cm⁻²
Key focus: low resistivity, low defect density
 
Example 2: For Optics/Photonics Research
Application: SiC-based photonic devices, nonlinear optics experiments
 
Recommended parameters:
Conductivity: High-purity undoped
Polytype: 4H-SiC or 6H-SiC
Size: 2–4", thickness 350–500 µm
Orientation: (0001)
Surface: DSP, ensuring transparency and low scattering
Key focus: transmittance, refractive index, defect density
 
Example 3: For RF Devices
Application: Microwave devices, power amplifiers
Recommended parameters:
Conductivity: Semi-insulating
Polytype: 4H-SiC
Size: 4"
Orientation: (0001)
Surface: SP
Key focus: high resistivity (>10⁶ Ω·cm), low dislocation density
 

Conclusion

 
The choice of SiC substrates depends heavily on the application:
Power devices → n-type 4H-SiC, low defect density, low resistivity.
Optics/Photonics → High-purity undoped, DSP, with emphasis on transmittance and refractive index.
RF devices → Semi-insulating, high resistivity, ensuring stable signal performance.
When communicating with suppliers, preparing a clear checklist of requirements can greatly improve selection efficiency.