Silicon has powered electronics for decades, but in power conversion it is hitting physical limits. Wide-bandgap (WBG) semiconductors — silicon carbide (SiC) and gallium nitride (GaN) — have a larger energy band gap and a much higher critical electric field, allowing devices that are smaller, faster and far more efficient than their silicon equivalents.
Working principle
A wider band gap means the material withstands a higher electric field before breaking down, so a WBG device of a given voltage rating can be much thinner, giving lower on-resistance and conduction loss. WBG devices also switch much faster, slashing switching losses and permitting higher frequencies — which shrinks the inductors and capacitors. Higher thermal conductivity (SiC) lets them run hotter with less cooling.
| Property | Si | SiC | GaN |
|---|---|---|---|
| Band gap (eV) | 1.1 | 3.3 | 3.4 |
| Switching speed | Moderate | Fast | Very fast |
| High-voltage | Limited | Excellent (kV) | Good (≤~650 V) |
| Sweet spot | Low cost | EV traction, grid | Chargers, RF, low-V |
Application splitRule of thumb: SiC dominates high-voltage, high-power applications (EV traction inverters, grid) while GaN dominates high-frequency, lower-voltage ones (compact chargers, data-centre supplies).
Applications
- EV traction inverters and on-board chargers (extending range)
- Ultra-compact phone/laptop chargers (GaN)
- Solar inverters, data-centre power and grid converters
References & further reading
- Millán et al., “A Survey of Wide Bandgap Power Semiconductor Devices,” IEEE Trans. Power Electronics, 2014.
- Kaminski & Hilt, “SiC and GaN devices – competition or coexistence?,” IEEE, 2012.
- Jones et al., “Review of Commercial GaN Power Devices,” IEEE Trans. Power Electronics, 2016.