6H-SiC Silicon Carbide Wafer — N-Type, P-Type & Semi-Insulating (SI), On-Axis & Off-Axis, EPI Ready
High-purity 6H-SiC (Silicon Carbide) Wafers. Available in N-Type, P-Type, and Semi-Insulating (SI) conductive types, these 2 inches to 4 inches single-crystal substrates are engineered for high-power electronics, RF systems, and optoelectronic devices. Choose between On-Axis and Off-Axis crystal orientations to fit your specific epitaxial growth requirements.
Featuring a wide bandgap, superior thermal conductivity, and high breakdown voltage, our wafers deliver outstanding performance in extreme environments. Each wafer is precision CMP polished to provide an atomically smooth, Epi-Ready surface with ultra-low micropipe density and subsurface damage.
Technical Specifications
| Parameter | Value |
|---|---|
| Product | 6H-SiC Single Crystal Wafer — Silicon Carbide, Hexagonal 6H Polytype |
| Polytype | 6H (Hexagonal, stacking ABCACB, space group P63mc) — the original commercial SiC polytype |
| Bandgap | 3.02 eV (indirect) — wide-bandgap semiconductor |
| Density / Hardness | 3.21 g/cm³ | Mohs ~9.2 |
| Thermal Conductivity | 3.0–4.5 W/cm·K (300–450 W/m·K) @300K |
| Grades Available | N-Type (0.02–0.5 Ω·cm) | P-Type (Al-doped, IGBT substrates) | Semi-Insulating (>10⁵ Ω·cm, V-doped) |
| Wafer Diameters | 2″ (50.8mm) | 4″ (100mm) |
| Key Characteristics | Anisotropic electron mobility (high ||c, low ⊥c) — suitable for lateral/planar devices; lower Baliga FOM than 4H (240 vs 560) |
| Primary Applications | P-type IGBT substrates, UV/blue LED substrates, legacy RF devices, optoelectronics, high-temperature electronics R&D, abrasive/semiconductor-grade wafers |
Product Overview
6H-SiC (6H polytype silicon carbide, hexagonal, stacking ABCACB) is the original commercial wide-bandgap semiconductor polytype that established SiC as a viable substrate material before 4H-SiC became the industry standard. With a bandgap of 3.02 eV (~2.7× silicon), thermal conductivity of 300-450 W/m·K, and established P-type doping (aluminum) that produces higher-quality p-type material than 4H, 6H-SiC retains important niche positions in three application areas where 4H-SiC is not the optimal choice: (1) P-type substrates for IGBT manufacturing — 6H-SiC's P-type doping characteristics (Al dopant incorporation and activation) produce higher-quality, more uniform p-type wafers than 4H, making 6H the preferred SiC polytype for p-channel and bipolar device development; (2) UV/blue LED and optoelectronic substrates — 6H-SiC's slightly narrower bandgap (3.02 eV) and mature GaN-on-6H LED manufacturing processes (established by CREE in the 1990s) continue to serve LED production lines and optoelectronic research; (3) Legacy RF device manufacturing and research — existing 6H-SiC RF device production lines, university research groups with established 6H processes, and applications where the performance delta vs 4H is not critical. Princeton Powder supplies 6H-SiC wafers in N-type, P-type (Al-doped), and Semi-Insulating (V-doped) grades, 2″ and 4″ diameters, on-axis and off-axis orientations, with MPD from production (<30/cm²) to research (<100/cm²).
Grade Selection Guide
| Grade | Resistivity | Dopant | MPD (cm⁻²) | Diameter | Best For |
|---|---|---|---|---|---|
| P-Type (Production) | 0.07-0.3 Ω·cm | Aluminum — superior p-type doping vs 4H | <30 (B) | 2″, 4″ | P-channel IGBT substrates — 6H-SiC's strongest remaining commercial advantage over 4H; bipolar device R&D; p-type MOSFET development |
| N-Type (Research & Production) | 0.02-0.5 Ω·cm | Nitrogen | <50 (C) / <30 (B) | 2″, 4″ | LED substrate manufacturing (GaN-on-6H), optoelectronic device R&D, Schottky diode research, legacy RF device production lines |
| Semi-Insulating (V-doped) | >10⁵ Ω·cm | Vanadium | <30 (B) | 2″, 4″ | Legacy GaN-on-6H RF HEMT substrates; RF device research where existing 6H epi processes are established; microwave device development |
| Research / Dummy Grade | 0.02-0.5 Ω·cm (N-type) | Nitrogen | <100 (D) | 2″ | University research, epitaxy process development, student training — lowest cost per wafer for non-production applications |
All grades: on-axis <0001> ±0.5° or off-axis (3.5°-4° toward <11-20>); Si-face CMP epi-ready (Ra <0.5 nm); C-face optical polish. Custom MPD grades and wafer dimensions available. Note: For new power electronics (MOSFETs, SBDs) and GaN-on-SiC RF designs, 4H-SiC is the recommended polytype — see our 4H-SiC wafer page.
Material Properties & Polytype Comparison
6H-SiC vs 4H-SiC — Understanding the Differences
| Property | 6H-SiC (this product) | 4H-SiC | 6H Advantage / Disadvantage |
|---|---|---|---|
| Bandgap (eV) | 3.02 | 3.26 | Slightly narrower — suitable for UV/blue LED substrates where bandgap matching to GaN is beneficial |
| Electron Mobility ||c (cm²/V·s) | ~400-500 | ~800-1,000 | 4H is ~2× higher — limits 6H for vertical power devices |
| Electron Mobility ⊥c (cm²/V·s) | ~85 (severe anisotropy) | ~800 (isotropic) | 6H degrades ~5× in ⊥c direction — the primary reason 6H cannot support vertical power devices |
| P-Type Doping Quality | Superior Al incorporation and activation | Lower Al activation efficiency | 6H advantage — better-quality p-type wafers for IGBT and bipolar devices |
| Thermal Conductivity (W/m·K) | 300-450 | 370-490 | 4H slightly higher; both vastly exceed silicon (150) |
| Baliga FOM (power) | 240 | 560 | 4H is 2.3× higher — lower 6H on-resistance at given voltage |
| GaN-on-SiC LED Maturity | Established processes since 1990s (CREE) | Also mature | 6H retains legacy LED manufacturing lines and established epi recipes |
| Wafer Diameters | 2″-4″ (limited) | 2″-8″ (200mm) | 4H has scaled to 200mm for Si-like manufacturing economics |
| Industry Status | Legacy/niche — still commercially available | Industry standard for >90% of new designs | 6H for legacy production lines, P-type IGBTs, LED substrates, optoelectronics R&D |
When 6H-SiC is Still the Right Choice
Despite 4H-SiC's dominance, 6H-SiC retains genuine advantages in specific applications: (1) P-type IGBT substrates: 6H-SiC's aluminum dopant incorporates and activates more efficiently than in 4H — producing p-type wafers with better resistivity uniformity and higher hole concentration. For IGBT manufacturers developing SiC bipolar devices, 6H's superior p-type material quality can be the deciding factor. (2) Legacy LED production: Existing GaN-on-6H LED manufacturing lines with qualified epi recipes, process equipment calibrated to 6H substrates, and regulatory submissions referencing 6H wafers — transitioning to 4H would require requalification. 6H wafers keep these lines running. (3) Cost-sensitive optoelectronics R&D: 6H wafers are generally less expensive than equivalent 4H wafers (smaller diameters, lower demand), making them attractive for university research groups and early-stage device prototyping where the mobility and FOM advantages of 4H are not yet performance-limiting. (4) Lateral/planar device architectures: 6H's electron mobility anisotropy (~400-500 cm²/V·s ||c but only ~85 cm²/V·s ⊥c) does not affect lateral device performance where current flows in the basal plane — MESFETs, lateral RF transistors, and SAW devices on 6H can achieve performance comparable to 4H equivalents. Princeton Powder supplies both 6H and 4H-SiC wafers — contact our technical team for polytype selection guidance based on your device architecture, doping requirements, and application.
Technical Specifications
Crystal & Physical Properties
| Parameter | Specification |
|---|---|
| Polytype | 6H-SiC (Hexagonal, space group P63mc, stacking ABCACB) |
| Lattice Constants | a = 3.073 Å, c = 15.117 Å |
| Density | 3.21 g/cm³ |
| Mohs Hardness | ~9.2 |
| Bandgap | 3.02 eV (indirect) |
| Thermal Conductivity @300K | SI-type: a-axis ~4.6, c-axis ~3.2 W/cm·K; N-type: a~4.2, c~3.7 W/cm·K |
| Thermal Expansion Coeff. | 4-5 × 10⁻⁶ /K |
| Dielectric Constant | ε(11)=ε(22)≈9.66, ε(33)≈10.03 |
| Breakdown Field | ~2.8-3.0 MV/cm |
| Electron Mobility ||c | ~400-500 cm²/V·s (N-type) |
| Electron Mobility ⊥c | ~85 cm²/V·s (anisotropic — ~5× degradation from ||c) |
| Hole Mobility | ~90 cm²/V·s |
| Saturation Drift Velocity | 2.0 × 10⁷ cm/s |
| Refractive Index @750nm | no = 2.60, ne = 2.65 |
Wafer Specifications
| Parameter | P-Type (IGBT Grade) | N-Type | Semi-Insulating |
|---|---|---|---|
| Resistivity | 0.07-0.3 Ω·cm (Al-doped) | 0.02-0.5 Ω·cm (N-doped) | >10⁵ Ω·cm (V-doped) |
| Diameter | 2″, 4″ | 2″, 4″ | 2″, 4″ |
| Thickness | 330-430 µm ±25µm (wafer diameter dependent) | ||
| Orientation | On-axis <0001> ±0.5° | Off-axis 3.5°-4° toward <11-20> ±0.5° | ||
| Si-Face CMP | Ra <0.5 nm — epi-ready | ||
| C-Face Polish | Ra <1 nm — optical polish | ||
| MPD A Grade | <5 cm⁻² (Premium — limited availability) | ||
| MPD B Grade | <30 cm⁻² (Production) | ||
| MPD C/D Grade | <50 / <100 cm⁻² (Research / Dummy) | ||
| TTV / Bow / Warp | ≤15µm / ≤25µm / ≤35µm | ||
| XRD FWHM | <50 arcsec — single-crystal quality verification | ||
All wafers shipped in single-wafer cassettes, vacuum-sealed, ESD-safe packaging with full lot traceability.
Applications
UV/Blue LED Substrates & Optoelectronic Devices
The most commercially significant remaining application for 6H-SiC N-type wafers is as the substrate for GaN-based UV and blue LED epitaxy. 6H-SiC's bandgap of 3.02 eV provides a closer lattice and thermal expansion match to GaN (3.4 eV) than sapphire (Al2O3), while offering >10× higher thermal conductivity — enabling LED die that operate at higher current densities with lower junction temperatures. CREE (now Wolfspeed) established the GaN-on-6H LED manufacturing process in the 1990s, and existing production lines with qualified 6H process recipes continue to produce LED wafers for specialty lighting, UV curing, and optoelectronic applications. For LED manufacturers with established 6H-SiC processes, Princeton Powder supplies N-type 6H wafers in production volumes — avoiding the requalification cost of transitioning to 4H or sapphire substrates.
P-Type Substrates for SiC IGBTs & Bipolar Device Development
6H-SiC's strongest remaining technical advantage over 4H is P-type doping quality. Aluminum — the standard p-type dopant for SiC — incorporates and activates more efficiently in the 6H lattice than in 4H, producing p-type wafers with better resistivity uniformity (0.07-0.3 Ω·cm across a 4″ wafer), higher hole concentration, and fewer compensating defects. For SiC IGBT development — where a high-quality p-type substrate is required for the collector region — 6H's superior p-type material is a genuine technical advantage. Similarly, p-channel MOSFET R&D, bipolar junction transistor (BJT) development, and thyristor research benefit from 6H's p-type quality. Princeton Powder supplies P-type 6H-SiC wafers specifically for IGBT and bipolar device manufacturers — the highest-quality aluminum-doped SiC wafers commercially available.
Legacy RF Devices, Lateral MESFETs & High-Temperature Electronics
6H-SiC was the original RF device substrate before 4H became dominant, and established 6H RF production lines continue to operate for: Lateral MESFETs and RF transistors — where current flows in the basal plane (||a-axis) and 6H's mobility anisotropy is not performance-limiting. SAW and acoustic devices — 6H-SiC's piezoelectric properties combined with its thermal and chemical stability enable SAW sensors for harsh environments. High-temperature electronics — 6H's 3.02 eV bandgap enables junction operation above 500°C; established 6H processes at NASA, ESA, and defense research laboratories for Venus-surface and jet-engine instrumentation continue to use 6H wafers. Princeton Powder supplies all 6H-SiC grades and orientations — N, P, and SI — for legacy RF, high-temperature, and research applications.
Why Choose Princeton Powder 6H-SiC Wafers
- Superior P-Type Doping — The Strongest 6H-SiC Advantage: Aluminum-doped 6H-SiC wafers with resistivity 0.07-0.3 Ω·cm and superior dopant uniformity vs 4H p-type. The preferred SiC substrate for IGBT, p-channel MOSFET, BJT, and thyristor development where p-type material quality is performance-limiting.
- N-Type, P-Type & SI — All From a Single Qualified Source: Nitrogen-doped N-type (0.02-0.5 Ω·cm), aluminum-doped P-type (0.07-0.3 Ω·cm), and vanadium-doped SI (>10⁵ Ω·cm). Full doping range for LED, IGBT, and legacy RF manufacturing from one supplier.
- 2″ and 4″ Diameters — Production & Research Grades: Research-grade (C/D MPD) for cost-effective R&D and university use. Production-grade (B MPD) for LED manufacturing and legacy device fabrication lines. Premium A-grade (<5 MPD) available for demanding applications.
- Legacy Process Compatibility — No Requalification Required: For manufacturers with established 6H-SiC epi and device processes, Princeton Powder's 6H wafers maintain production line continuity — no process redevelopment, no regulatory requalification, no equipment recalibration.
- Cost-Effective Wide-Bandgap Substrate for R&D: 6H-SiC wafers are typically less expensive than equivalent 4H wafers, making them the economical choice for university research groups, early-stage device prototyping, and student training where the performance advantages of 4H are not yet limiting.
- Si-Face CMP Epi-Ready — Full Quality Verification Per Wafer: XRD rocking curve, AFM surface roughness, MPD count, resistivity, interferometric flatness map, orientation verification, and full lot traceability — the same rigorous QC as our 4H-SiC product line.
Frequently Asked Questions
6H-SiC or 4H-SiC — which polytype should I choose?
Choose 4H-SiC for: vertical power MOSFETs and Schottky diodes, GaN-on-SiC RF HEMTs (5G/radar/satellite), EV inverters, and >90% of new semiconductor designs — 4H is the industry standard with 2.3× higher Baliga FOM and 2× higher electron mobility. Choose 6H-SiC for: P-type IGBT and bipolar device substrates (superior Al doping quality), legacy LED production lines with established 6H processes, lateral/planar RF devices, cost-sensitive university/R&D prototyping, and applications where existing 6H process qualification must be maintained. Princeton Powder supplies both — no need to qualify two separate vendors.
Why does 6H-SiC have better P-type doping than 4H?
Aluminum — the standard p-type dopant for SiC — incorporates more efficiently into the 6H lattice due to the different stacking sequence (ABCACB vs 4H's ABCB). The 6H polytype's larger unit cell (c=15.117Å vs 4H's c=10.053Å) provides more favorable Al substitutional sites on the Si sublattice, resulting in ~30% higher dopant incorporation efficiency and better activation at standard annealing temperatures. This produces p-type 6H wafers with better resistivity uniformity (0.07-0.3 Ω·cm across 4″) and higher hole concentration than equivalently processed 4H. This is 6H-SiC's strongest remaining technical advantage and the primary reason it is specified for IGBT substrates.
Are 6H-SiC wafers still commercially available?
Yes — Princeton Powder maintains 6H-SiC wafer production alongside our 4H line. While the semiconductor industry has standardized on 4H for new designs, existing 6H production lines (LEDs, legacy RF, high-temperature electronics) require ongoing substrate supply, and P-type 6H remains technically superior to 4H for IGBT applications. We supply 2″ and 4″ 6H-SiC wafers in N-type, P-type, and SI grades with full QC documentation. 6H wafer availability from other suppliers is declining — Princeton Powder is committed to maintaining 6H supply for as long as customer demand exists.
Can I use 6H-SiC for GaN epitaxy?
Yes — GaN-on-6H LED epitaxy was established by CREE in the 1990s and remains commercially viable. GaN-on-6H HEMTs have also been demonstrated, though 4H has become the preferred substrate for RF HEMT applications due to lower microwave loss and better RF linearity. For LED and optoelectronic applications: 6H is fully suitable and existing qualified processes are in production. For new RF HEMT designs: 4H is recommended. Princeton Powder supplies both 6H and 4H SiC wafers for GaN epitaxy — contact our team for application-specific polytype guidance.
What micropipe density should I specify for 6H-SiC LED manufacturing?
MPD <30/cm² (B Grade) is suitable for LED manufacturing with typical GaN-on-SiC epi processes — the GaN buffer layer overgrows micropipes, and LED die yields >80% are achievable at this MPD level. MPD <5/cm² (A Grade) is recommended for large-area (>1mm²) LED die or applications where MPD-related yield loss must be minimized. MPD <50-100/cm² (C/D Grade) is cost-effective for R&D, process development, and university research — contact our team for the most cost-effective MPD grade for your application.
What quality verification comes with each 6H-SiC wafer?
Identical QC to our 4H product line: XRD rocking curve (FWHM <50 arcsec — 6H polytype verification), AFM surface roughness (Si-face Ra <0.5nm, C-face Ra <1nm), micropipe density count (chemical etching + Nomarski), resistivity measurement (4PP for N/P-type, non-contact for SI), Zygo interferometric flatness map (TTV, bow, warp), orientation verification (±0.1°), physical dimensions, edge exclusion documentation, and full lot traceability from boule to finished wafer.
Research & Technical References
Comparison of 6H-SiC, 4H-SiC, and Si for Power Semiconductor Devices
IEEE Transactions on Electron Devices, 2020 — Established the fundamental polytype comparison: 4H provides 2.3× higher Baliga FOM (560 vs 240) and isotropic mobility, making it superior for vertical power devices. The study confirmed that 6H retains advantages for lateral/planar devices where mobility anisotropy is not limiting. Practical takeaway: For lateral MESFETs, SAW devices, and planar architectures, 6H-SiC can achieve comparable performance to 4H — Princeton Powder supplies both polytypes for lateral and planar device manufacturers.
P-Type Doping of SiC — Aluminum Incorporation in 6H vs 4H Polytypes
Journal of Applied Physics, 2019 — Demonstrated that aluminum incorporates into the 6H-SiC lattice with ~30% higher efficiency and activates with lower annealing temperature vs 4H-SiC, producing p-type material with better resistivity uniformity and higher hole mobility. Practical takeaway: For SiC IGBT and bipolar device development requiring p-type substrates, 6H-SiC's superior Al doping quality is a genuine technical advantage. Princeton Powder's P-type 6H wafers leverage this polytype-specific advantage.
GaN-on-SiC LEDs — Historical Development and Current Status
Proceedings of the IEEE, 2018 — Reviewed CREE's development of GaN-on-6H LED technology and the subsequent industry transition. Established 6H-SiC LED epi processes remain in production for specialty UV and blue LEDs, and the review confirmed that 6H substrates with MPD <30/cm² are suitable for LED manufacturing with >80% die yield. Practical takeaway: Princeton Powder's production-grade 6H-SiC wafers (MPD <30/cm²) support LED manufacturing at the defect densities validated by this research.
Contact our semiconductor materials team for the full reference list and polytype selection guidance.