I. Current Status of the Silicon Carbide Industry and Its Application Prospects

Silicon carbide (SiC) is valued for its outstanding physical and chemical properties, making it indispensable in industrial manufacturing, aerospace, defense, and semiconductor technologies. Traditionally, its high hardness—second only to diamond—has made it a key abrasive material for grinding and polishing. Its excellent thermal stability, oxidation resistance, and mechanical strength also enable its use in refractory components.
In aerospace and defense, SiC and its composites provide lightweight, high-strength, and high-temperature resistance for turbine blades, engine parts, ceramic armor, radomes, and radar systems. As a representative wide-bandgap semiconductor, SiC supports high-temperature, high-voltage, high-frequency, and high-power operation, driving its adoption in electric vehicles, renewable energy, power electronics, photovoltaics, and smart manufacturing.
The global SiC market is growing rapidly. Driven by EV main inverters, the SiC power device market is projected to reach USD 6.3 billion by 2027. Material cost accounts for ~70% of the overall value chain, making breakthroughs in upstream crystal growth and substrate technology critical for industry development.

II. Categories of Defects in SiC Single Crystal Growth

The SiC industry chain includes powder preparation, crystal growth, substrate fabrication, epitaxy, wafer processing, and device manufacturing. Defects formed during crystal growth, wafer preparation, and epitaxy significantly influence device performance—including on-resistance, leakage current, breakdown voltage, and long-term reliability—and may ultimately lead to device failure. Defect control is therefore central to improving SiC device yield.
China’s national standard GB/T 43612-2023 “Defect Atlas of Silicon Carbide Crystal Materials” classifies SiC defects into four major categories:

 

1. Ingrown Defects

Defects generated during PVT growth due to seed-crystal inheritance, stoichiometric imbalance, internal stress, or impurities.

 

2. Substrate Defects

Structural defects inherent to the substrate and process-induced defects from cutting, grinding, and polishing.

 

3. Epitaxial Defects

Growth-related crystal defects within epitaxial layers and surface morphological defects derived from step-flow growth mechanisms.

 

4. Process-Induced Defects

Deep-level or non-intrinsic structural defects introduced during device fabrication.
 
 

III. Common Defect Types in SiC Single Crystals

SiC defects can be categorized into bulk crystal defects and surface/near-surface defects.

1. Bulk Crystal Defects

(1) Dislocations (TSD, TED, BPD)

Dislocations are the primary causes of performance degradation in SiC power devices.
Threading Screw Dislocations (TSDs): Penetrating defects with Burgers vectors along ⟨0001⟩, typically 10²–10³ cm⁻².
Threading Edge Dislocations (TEDs): Penetrating defects with Burgers vectors of 1/3⟨11–20⟩ and roughly ten times the density of TSDs.
Basal Plane Dislocations (BPDs): Located on the (0001) basal plane, with a density of ~1500 cm⁻²; they impact gate oxide reliability and on-resistance.
BPDs often nucleate near the shoulder region of crystal boules and propagate during cooling under thermal-stress-driven glide.

(2) Micropipes (MPs)

Hollow core defects extending along the growth direction, typically 0.1–10 μm in diameter. Micropipes severely limit device current capability and induce leakage, making them one of the most harmful defect types. Their origins include carbon inclusions, seed-crystal inheritance, and micropipe coalescence.

(3) Stacking Faults (SFs)

Local disruptions in the stacking sequence of the basal plane, generally <1 cm⁻², displaying triangular photoluminescence signatures. They may originate from substrate inheritance or expansion of BPDs.

2. Surface and Near-Surface Defects

(a) Carrot Defects

A common epitaxial defect formed through interactions between TSDs and SFs. Their morphology is correlated with prismatic stacking faults, and they can degrade blocking performance.

(b) Scratches

Generated during polishing or handling. Scratches can trigger defect formation in epitaxy, such as high-density dislocations or carrot defects, highlighting the importance of high-quality wafer surface preparation.

(c) Triangular Defects

One of the most prevalent epitaxial defects, typically caused by particle contamination leading to 3C-SiC polytype inclusions. They significantly impact device yield.

(d) Step Bunching

A typical morphological defect in epitaxy, increasing interface roughness, causing electric-field concentration, and degrading breakdown voltage and MOSFET channel mobility.

 

IV. Research Progress in SiC Defect Control

To reduce defect density and enhance crystal quality, research focuses on seed optimization, growth-interface engineering, and process improvements.

1. High-Quality Seed Preparation

Most defects originate from the seed; thus, seed quality is fundamental. The repeated-a-face (RAF) method changes the growth direction to prevent dislocations and micropipes from propagating, significantly reducing defect density. However, RAF growth is complex and time-intensive, and further optimization is needed for mass production.

2. Optimization of Seed Surface and Growth Interface

High-quality surface treatment and interface engineering effectively reduce defect nucleation and are essential strategies for improving boule quality.

3. Process and Equipment Optimization

Different growth technologies exhibit distinct capabilities for defect control:
Solution Growth: Lower temperature, easier control of defect density.
PVT (Sublimation) Growth: Enables large-size crystal production but faces greater challenges in defect suppression.
Mitani et al. proposed a hybrid “solution + PVT” approach in which a threading dislocation conversion layer is formed through solution growth, followed by PVT sublimation growth. This method effectively suppresses defect inheritance. Additionally, step-flow growth in solution systems can convert vertical dislocations into stacking faults aligned with step edges, preventing further propagation.

V. Conclusion

Although significant progress has been made in defect control of SiC single crystals, challenges remain in achieving stable, large-scale production of high-quality crystals. With advances in multiscale simulation, in-situ monitoring, and intelligent control technologies, future SiC crystal growth is expected to achieve more precise defect management, further supporting the development of high-performance power devices.