Frequently Asked Questions
What is the difference between 4H-SiC and 6H-SiC?
They are different crystal structures (polytypes). 4H-SiC has a wider bandgap of about 3.26 eV and higher electron mobility, which makes it the standard for power devices. 6H-SiC has a bandgap of about 3.0 eV and is used in some research and optoelectronic work.
Should I choose N-type or semi-insulating SiC?
N-type wafers are conductive and are used for vertical power devices such as MOSFETs and Schottky diodes. Semi-insulating wafers have very high resistivity and are used for RF devices, such as GaN HEMTs grown on SiC.
What do production, research and dummy grade mean?
Production grade has the lowest defect levels for device manufacturing. Research grade allows more defects and suits experiments. Dummy grade is for equipment setup, process testing and handling practice.
What sizes of SiC wafers are available?
Wafers are offered at 2, 4, 6 and 8 inch diameters, plus small square pieces such as 5 mm x 5 mm. Custom sizes and SiC epitaxial wafers are also available.
Why use silicon carbide instead of silicon?
SiC has a wide bandgap, a higher breakdown field and better thermal conductivity than silicon. Devices made on SiC can run at higher voltages, higher temperatures and with lower energy losses.
What to know before you buy
This collection runs from 10 x 10 mm research grade squares to full 2, 4, 6 and 8 inch wafers. It covers the 4H, 6H and 3C polytypes in N-type, P-type, semi-insulating and high purity (undoped) semi-insulating, or HPSI, forms.
For device and epitaxy work on full wafers, look at the 6 inch 4H-SiC wafers, N-type or semi-insulating, or the 8 inch 4H-SiC N-type wafers. HPSI wafers come in 4, 6 and 8 inch for RF work that needs very high resistivity. For early trials, small squares let you test growth and processing before committing full wafers. Options include the 10 x 10 mm 4H N-type research grade substrate, 6H semi-insulating squares with a double side polished version, and an A-plane 4H N-type square.
Grade matters too. Research grade suits experiments where surface and crystal quality affect results. Dummy grade wafers, such as the 2 inch 3C-N type wafers and the 2 inch P-type wafers, suit tool setup, calibration and handling practice. As-cut 4H N-type wafers are unpolished, for labs that do their own lapping and polishing. For background on the material, read The Differences Between Silicon and Silicon Carbide.
