As the world moves toward carbon neutrality and greater energy efficiency, a new generation of wide bandgap (WBG) semiconductors is reshaping the landscape of power and optoelectronic devices. Among them, Silicon Carbide (SiC) has emerged as a key material driving this transformation.
When used as a substrate, SiC not only supports high-quality homoepitaxial growth but also serves as an excellent foundation for various heteroepitaxial wide and ultra-wide bandgap materials, demonstrating outstanding compatibility and application potential.

1. Unique Advantages of SiC Substrates

Silicon carbide is a chemically stable, thermally conductive, and high–breakdown-field semiconductor. The most widely used form, 4H-SiC, has the following representative physical parameters:
Bandgap (Eg): ~3.26 eV
Thermal conductivity: up to 490 W/m·K
Critical electric field: ~3 MV/cm
Electron saturation drift velocity: 2.0×10⁷ cm/s
These properties enable SiC-based devices to operate efficiently under high temperature, high voltage, and high frequency conditions, making SiC an ideal substrate material for power electronics.

2. SiC Homoepitaxy — The Foundation for High-Performance Power Devices

In homoepitaxial growth, a SiC epitaxial layer is deposited on a SiC substrate using Chemical Vapor Deposition (CVD).
A typical structure is:

This configuration is widely applied in SiC MOSFETs and Schottky Barrier Diodes (SBDs).
By precisely controlling the epitaxial layer thickness and doping concentration, engineers can balance breakdown voltage and on-resistance, significantly improving overall device performance and energy efficiency.

3. Heteroepitaxy on SiC — Expanding the Device Landscape

Thanks to its excellent lattice compatibility with various wide bandgap materials, SiC is also an outstanding substrate for heteroepitaxial growth systems.

(1) GaN-on-SiC — The Perfect Combination of High Power and High Frequency

In RF and 5G communication applications, GaN-on-SiC has become the mainstream epitaxial structure.
Its typical layer stack is:

This structure combines the high electron mobility of GaN with the superior thermal conductivity of SiC, achieving excellent power density and frequency performance.
It is widely used in radar systems, satellite communications, and RF power amplifiers.

(2) AlN-on-SiC — A New Direction for Deep-UV Emission

Aluminum nitride (AlN) is nearly lattice-matched to SiC (mismatch < 1%), making it an ideal material for deep ultraviolet (DUV) optoelectronics.
Epitaxial AlN layers grown on SiC feature low strain and low defect density, significantly improving light extraction efficiency and device lifetime for DUV LEDs.

(3) β-Ga₂O₃-on-SiC — Stepping into the Ultra-Wide Bandgap Era

Gallium oxide (β-Ga₂O₃) has a bandgap as wide as 4.9 eV, making it a leading ultra-wide bandgap semiconductor.
Although its lattice mismatch with SiC is relatively large, high-quality heteroepitaxy can be achieved using buffer layers (such as Al₂O₃ or GaN).
This opens new possibilities for ultra–high-voltage power devices and next-generation energy electronics.

4. Typical Epitaxial Growth Techniques

Different material systems require different epitaxial technologies, summarized as follows:
 

Epitaxial System	Common Technique	Key Advantages
SiC	CVD	High-quality homoepitaxy, controllable thickness and doping
GaN / AlN	MOCVD	Excellent uniformity, suitable for large-scale production
β-Ga₂O₃	MBE / HVPE	Enables thick-layer growth for high-voltage applications

By optimizing parameters such as temperature, pressure, and V/III ratio, it is possible to minimize defect density and interfacial stress, thereby improving epitaxial layer quality.

5. Conclusion — SiC as the Bridge Between Today and the Future

From SiC homoepitaxy for power electronics to GaN-on-SiC for RF communications and AlN-on-SiC for deep-UV optoelectronics, silicon carbide has proven to be the ideal substrate for a wide range of advanced semiconductor applications.
As epitaxial growth technologies continue to evolve and material costs decrease, SiC will play an even more critical role in enabling high-efficiency energy systems, smart manufacturing, and next-generation information technologies — becoming a true cornerstone of the wide bandgap semiconductor era.