Silicon Carbide
Properties
Silicon Carbide
Properties
| Silicon carbide (SiC) is a Wide bandgap semiconductor
that possesses extremely high thermal, chemical, and mechanical stability.
SiC is by far the most developed among wide bandgap semiconductors due
to the availability of high quality SiC substrates, advances in chemical-vapor-deposition
(CVD) growth of epitaxial structures, the ability to easily dope the material
n and p type and ability to produce high-quality native oxide.
SiC has over 170 polytypes. Each of SiC polytypes has different physical properties. The most commonly known polytypes are 3C-SiC, 4H-SiC and 6H-SiC, but only the last two are commercially available. 4H-SiC is preferred for power devices because of its high carrier mobility and its low dopant ionization energy. |
| Material | Bandgap Eg
(eV) |
ni
(cm-3) |
Electron Mobility
(cm2/V/s) |
EC
(MV/cm) |
vsat
(107cm/s) |
Thermal Conductivity
(W/cm/K) |
| Si | 1.12 | 1.5 x 1010 | 1400 | 0.3 | 1.0 | 1.5 |
| GaN | 3.39 | 1.9 x 10-10 | 1000 | 3.3 | 2.5 | 1.3 |
| 3C-SiC | 2.20 | 6.9 | 800 | 2 | 2.0 | 5 |
| 4H-SiC | 3.26 | 8.2 x 10-9 | 960 ( // c-axis)
800 ( | c-axis) |
3 | 2.0 | 4.9 |
| 6H-SiC | 3.00 | 2.3 x 10-6 | 400 ( // c-axis)
85 ( | c-axis) |
3 | 2.0 | 4.9 |
| Diamond | 5.5 | 1.6 x 10-27 | 2200 | 5.6 | 2.7 | 20 |
| Several figures of merit (FOM) have been proposed to quantify the performance improvement with SiC. For unipolar power switching devices, SiC offers more than 500 times improvment over Si. |
| JFOM | KFOM | BFOM | BHFFOM | |
| Si | 1 | 1 | 1 | 1 |
| 3C-SiC | 280 | 5.8 | 140 | 25 |
| 4H-SiC | 400 | 5.1 | 560 | 69 |
| 6H-SiC | 400 | 5.1 | 240 | 29 |
| Note:
JFOM: Johnson's FOM for high frequency, high power discrete amplifiers; KFOM: Keyes' FOM for high speed switches; BFOM: Baliga's FOM for low-frequency, high-power unipolar switches; BHFFOM: Baliga's FOM for high-frequency, high-power unipolar switches. |