4H-SiC Substrate & Wafer — Wide Bandgap Power Semiconductor Guide
- Material: 4H-Silicon Carbide (SiC)
- Crystal Structure: Hexagonal (4H polytype)
- Bandgap: ~3.26 eV
- Thermal Conductivity: ~490 W/m·K
- Breakdown Field: ~3 MV/cm
- Typical Diameters: 2″ / 4″ / 6″ (150 mm emerging)
- Applications: Power MOSFETs, Schottky diodes, RF & EV electronics
4H-SiC (4H-Silicon Carbide) is the dominant wide-bandgap semiconductor substrate for next-generation power electronics and high-temperature devices. Compared with silicon, 4H-SiC offers a much wider bandgap, significantly higher breakdown electric field, superior thermal conductivity, and excellent chemical stability.
These properties make 4H-SiC substrates and wafers essential for high-voltage, high-power, and high-frequency devices, including EV inverters, fast chargers, renewable-energy converters, and RF electronics. This guide explains how 4H-SiC crystals are grown, wafer specifications, doping and orientation options, surface quality requirements, and how to order device-grade or epitaxy-ready 4H-SiC wafers.
SECTION A — Crystal Growth of 4H-SiC
Physical Vapor Transport (PVT)
4H-SiC single crystals are grown almost exclusively by the Physical Vapor Transport (PVT) method at temperatures above 2000 °C. This method enables:
- Large-diameter boule growth
- Controlled polytype stability (4H dominance)
- High crystal purity
- Low impurity incorporation
Polytype Control
Among SiC polytypes (4H, 6H, 3C), 4H-SiC is preferred due to:
- Higher electron mobility than 6H-SiC
- Superior breakdown characteristics
- Mature industrial device ecosystem
SECTION B — Doping Types & Electrical Properties
Common conductivity types
| Doping Type | Dopant | Typical Resistivity |
|---|---|---|
| n-type | Nitrogen (N) | 0.015 – 0.03 Ω·cm |
| semi-insulating | Vanadium (V) | >10⁵ Ω·cm |
n-type 4H-SiC is widely used for power devices and epitaxial growth, while semi-insulating 4H-SiC is preferred for RF and microwave applications.
SECTION C — Wafer Orientation & Cut
Standard orientations
- (0001) Si-face — dominant for power devices
- (000-1) C-face — specialized epitaxial growth
Off-axis angles
- 4° off-axis (most common)
- 8° off-axis (legacy processes)
Off-axis wafers suppress polytype inclusions and improve step-flow epitaxy.
SECTION D — Surface Quality & Polishing
High-performance SiC devices require ultra-high surface quality. Typical specifications include:
- Surface roughness: Ra ≤ 0.2 nm (epi-ready)
- Scratch-dig: ≤ 20-10
- TTV: ≤ 10 μm
- Bow / Warp: tightly controlled per SEMI standards
Wafers may be supplied as:
- As-polished (device fabrication)
- Epi-ready (for CVD epitaxy)
SECTION E — Defects & Material Quality
Key defect metrics
- Micropipe density (MPD): < 0.1 cm⁻² (state-of-the-art)
- Basal plane dislocations (BPD)
- Threading screw / edge dislocations
Low defect density is critical for high-yield power MOSFETs and diodes. Advanced boule growth and wafer processing significantly reduce device-killing defects.
SECTION F — Applications of 4H-SiC Substrates
Power Electronics
- SiC MOSFETs
- Schottky barrier diodes (SBD)
- Power modules for EVs and rail
Energy & Infrastructure
- Fast chargers
- Solar and wind inverters
- Smart grid systems
RF & High-Frequency Devices
- GaN-on-SiC RF amplifiers
- Radar and satellite electronics
Recommended 4H-SiC Substrates & Custom Wafer Solutions
The following 4H-SiC substrates and wafers are commonly used in power device fabrication and epitaxial growth. Custom diameter, doping level, orientation, and surface preparation are available upon request.
SECTION G — How to Order 4H-SiC Substrates or Wafers
- Diameter (2″ / 4″ / 6″)
- Conductivity type (n-type or semi-insulating)
- Resistivity range
- Orientation & off-axis angle
- Surface finish (polished / epi-ready)
- Defect density requirements
Design-Realized also supports custom wafer specs, R&D-scale orders, and research-grade substrates.
