Silicon carbide (SiC) and gallium nitride (GaN) are wide bandgap semiconductors whose band gaps, roughly 3.2 to 3.4 eV, are about three times larger than silicon's 1.12 eV, which lets them block far higher voltages in thinner device layers and switch with lower losses (Fujita, Jpn. J. Appl. Phys. 2015). In practice SiC dominates high-voltage, high-power work such as electric-vehicle traction inverters, while GaN leads in fast, compact converters at 650 V and below, such as phone and laptop chargers, and in radio-frequency amplifiers.

• Both materials have a critical breakdown field ten or more times that of silicon, which is the main reason they make better power switches (Fujita 2015).
• In widely cited comparison tables, SiC's thermal conductivity is roughly three to four times that of GaN or silicon (Fujita 2015; Ozpineci and Tolbert, ORNL 2003), and SiC can be grown as large single-crystal wafers, which enables vertical, high-voltage devices.
• Commercial SiC MOSFETs span roughly 650 V to 1700 V; commercial GaN transistors are lateral devices aimed mostly at 600 V and below (Rafin et al., Micromachines 2023).
• GaN is usually grown on silicon wafers, which keeps cost down; Infineon announced 300 mm GaN-on-silicon power wafers in 2024 (Semiconductor Today).
• Gallium oxide and diamond have even wider gaps but face doping, substrate, or heat-removal problems that keep them mostly in research (Xu et al., Oxford Open Materials Science 2022).

What is a wide bandgap semiconductor?

A semiconductor's band gap is the energy needed to lift an electron from the filled valence band into the empty conduction band (see our explainer, What is a band gap?). Conventional semiconductors such as silicon and germanium have gaps of roughly 0.7 to 1.5 eV, while wide bandgap materials are generally defined as those with gaps above about 2 eV (Wikipedia). The group includes SiC and GaN. A 2022 review classes the related nitride aluminum nitride (AlN), together with gallium oxide and diamond, as "ultrawide" bandgap materials (Xu et al. 2022).

A wider gap matters for three practical reasons:

• Higher breakdown field. It takes a much stronger electric field to tear electrons loose across a wide gap, so a device can hold off more voltage before avalanche breakdown.
• Higher operating temperature. Fewer electrons are thermally excited across a wide gap, so leakage stays low when the device is hot. Wide bandgap devices can in principle operate at temperatures on the order of 300 °C (Wikipedia).
• Faster, lower-loss switching. Because the blocking layer can be made thinner and more heavily doped, the same voltage rating comes with less stored charge and lower resistance.

Why does breakdown field matter so much for power devices?

In a power transistor or diode, a lightly doped "drift region" holds off the voltage when the device is off. Classic device physics gives the breakdown voltage, for a given doping level, as proportional to the square of the critical field, and the specific on-resistance of the drift region as inversely proportional to the cube of the critical field times the carrier mobility (Ozpineci and Tolbert, ORNL report 2003). Because of that cubic dependence, a tenfold increase in critical field is worth far more than a modest loss of mobility.

Ozpineci and Tolbert's Oak Ridge National Laboratory comparison found that, for the same voltage rating, a silicon device needs a drift region roughly ten times thicker than SiC or GaN, and that the drift-region on-resistance of silicon is roughly ten times higher (Ozpineci and Tolbert 2003). Lower on-resistance means less conduction loss, and smaller devices mean less capacitance and faster switching. These gains let designers raise switching frequency, which shrinks the inductors, capacitors and transformers that dominate the size and weight of a power converter.

GaN vs SiC vs silicon: how do the properties compare?

The table below uses a single, consistent source so the numbers are comparable. Published values vary between references, especially for breakdown field, mobility and thermal conductivity, so treat them as representative room-temperature figures rather than design data.

Source: Table I of Fujita, Jpn. J. Appl. Phys. 54, 030101 (2015). Reported GaN mobility depends strongly on whether bulk material or a heterostructure channel is meant, which is one reason figures differ between sources.

Two patterns stand out. First, GaN and SiC have broadly similar band gaps and breakdown fields, so neither has a decisive advantage on paper for blocking voltage. Second, SiC's thermal conductivity is several times higher than GaN's, which matters when a device must dissipate kilowatts. The 2003 comparison by Ozpineci and Tolbert even listed GaN's thermal conductivity (1.3 W/cm·K) below silicon's (1.5 W/cm·K) and noted that growing GaN on SiC wafers improves overall heat removal, though not to the level of SiC itself (Ozpineci and Tolbert 2003).

Computed values tell a different story in absolute terms. Density functional theory (DFT) with the PBE functional, the method behind most large materials databases, underestimates band gaps; the Materials Project reports an average underestimate factor of about 1.6 against experiment (Materials Project documentation). For example, the representative computed gap shown on LatticeGraph's GaN page is about 1.7 eV, against a measured 3.39 eV. On the SiC page, the representative entry is a long-period polytype computed at about 1.8 eV, and the 4H-SiC entry is computed at about 2.2 eV, against a measured 3.23 eV. The ranking is still informative, but the absolute numbers should not be read as measurements.

What is 4H-SiC, and why does polytype matter?

Silicon carbide is unusual in that the same composition crystallizes in many stacking sequences called polytypes; the Ioffe Institute's semiconductor database notes more than 200 of them, and about 95% of publications deal with three of them: cubic 3C and hexagonal 4H and 6H (Ioffe Institute, SiC basic parameters; SiC band structure). The polytypes have different electronic properties. At 300 K the band gap of 4H-SiC is about 3.23 eV, while that of 3C-SiC is about 2.36 eV (Ioffe Institute, SiC band structure).

Power electronics uses 4H-SiC almost exclusively, and it is the polytype on which the commercial wafer and device supply chain has been built. Growing large crystals of a single polytype with low defect density is demanding, which has historically made SiC substrates expensive. Wafer sizes have grown steadily: in April 2022 Wolfspeed opened a fab in Marcy, New York, which it described as the world's first and largest 200 mm SiC fab (Wolfspeed press release, 2022), and in January 2026 the company reported producing a single-crystal 300 mm SiC wafer, a development milestone rather than a commercial product (Wolfspeed, 2026).

SiC also has a practical advantage over GaN that is easy to overlook: it uses the same gate oxide as silicon, SiO2, whereas GaN has no native oxide, so SiC MOSFETs can borrow much of silicon's metal-oxide-semiconductor process know-how (Ozpineci and Tolbert 2003).

Where does SiC win?

SiC's strengths are high voltage, high current and good heat removal. Because SiC wafers are available, devices can be built vertically, with current flowing through the thickness of the wafer, the same architecture used for silicon IGBTs and power MOSFETs. A 2023 review in Micromachines notes that SiC MOSFETs are commercially available from 650 V to 1700 V, with modules carrying roughly 5 to 600 A, and that devices rated above 10 kV are under development (Rafin et al., Micromachines 2023).

The flagship application is the electric-vehicle traction inverter, which converts DC battery power to AC for the motor. Silicon IGBTs have long dominated this medium-power range. Tesla's Model 3, introduced in 2017, was the first electric vehicle with inverters based on SiC MOSFETs (Rafin et al. 2023); according to IDTechEx, the MOSFETs were sourced from STMicroelectronics for an in-house inverter design (IDTechEx via PR Newswire). Other common SiC applications include on-board chargers, fast-charging stations, solar and storage inverters, industrial motor drives, and rail traction.

Where does GaN win?

GaN's advantage is speed. Most GaN power transistors are high-electron-mobility transistors (HEMTs): a thin aluminum gallium nitride layer on GaN creates a sheet of highly mobile electrons at the interface, the "two-dimensional electron gas," without deliberate doping. Because current flows laterally along the surface, these devices are well suited to high frequency but are harder to scale to very high voltage. The Micromachines review describes GaN as more effective for high-frequency applications based on lateral transistors, commercialized for 600 V and lower (Rafin et al. 2023).

GaN transistors are usually built by growing a thin GaN layer on a standard silicon wafer, known as GaN-on-Si (Wikipedia: Gallium nitride). This lets manufacturers use existing silicon fabs, a cost benefit the Micromachines review highlights (Rafin et al. 2023). In September 2024 Infineon said it had produced power GaN on 300 mm wafers in its Villach, Austria fab, noting that 300 mm wafers yield 2.3 times more chips per wafer than 200 mm wafers (Semiconductor Today, 2024).

Typical GaN applications:

• Consumer power adapters. GaN power transistors have been used increasingly in consumer power supplies since the early 2020s, allowing noticeably smaller USB-PD chargers (Wikipedia).
• Data-center and telecom power supplies, where high switching frequency improves power density.
• Radio-frequency amplifiers, including radar; GaN transistors suit high-frequency, high-voltage and high-temperature operation (Wikipedia).
• Optoelectronics. GaN made high-brightness blue LEDs and violet laser diodes possible (Wikipedia).

GaN vs SiC: which should you choose?

The choice is mostly set by voltage, power level and switching frequency. The two overlap around 650 V, where both are offered.

Sources: voltage ranges and structures from Rafin et al. 2023; wafer sizes from Wolfspeed (2022), Wolfspeed (2026) and Semiconductor Today.

Native GaN substrates exist but remain small and expensive. The Micromachines review reports bulk GaN wafers of 2-inch diameter at roughly ten times the cost of SiC and up to one hundred times that of silicon (Rafin et al. 2023). That cost gap is the main reason vertical GaN devices, which could compete with SiC at high voltage, remain a niche.

What comes after GaN and SiC: gallium oxide and diamond?

Two "ultrawide" bandgap materials attract attention because their breakdown fields are higher still. Beta-phase gallium oxide (Ga2O3) has a gap of about 4.8 to 4.9 eV and a breakdown field near 8 MV/cm (Fujita 2015). Its big attraction is manufacturing: bulk crystals can be grown from the melt by methods including edge-defined film-fed growth and Czochralski pulling, and wafers up to 4 inches have been commercialized (Xu et al. 2022). Its weaknesses are low thermal conductivity, around 0.2 W/cm·K in Fujita's table, and the lack of practical p-type doping, which a 2022 review attributes to large acceptor ionization energies and self-trapping of holes (Xu et al. 2022).

Diamond has the best numbers in the table, including a thermal conductivity of 20 W/cm·K (Fujita 2015), but its dopants are deep: boron and phosphorus have activation energies of about 0.37 and 0.59 eV, and commercial single-crystal diamond substrates are only available up to about 10 mm (Xu et al. 2022). For now both materials are mostly in research and early device demonstrations, while SiC and GaN carry commercial volume.

Frequently asked questions

Is GaN better than SiC?

Neither is better overall. GaN switches faster and is cheaper to make on silicon wafers, which favors compact converters at 650 V and below; SiC handles higher voltages and dissipates heat better, which favors high-power systems such as EV traction inverters.

Why is silicon carbide used in electric vehicles?

SiC MOSFETs reach 1200 V and above with low conduction and switching losses, so inverters and on-board chargers can be smaller and more efficient than silicon IGBT designs. Its high thermal conductivity also helps remove heat at kilowatt power levels.

What is the band gap of GaN and SiC?

Measured gaps are about 3.39 eV for wurtzite GaN and about 3.2 to 3.23 eV for 4H-SiC at room temperature (Fujita 2015; Ioffe). Computed DFT-PBE values in materials databases are substantially lower.

Why are GaN chargers smaller?

GaN transistors switch efficiently at higher frequencies, which allows smaller transformers, inductors and capacitors, and they generate less waste heat that would otherwise require bulk for cooling.

Will gallium oxide replace SiC?

Not in the near term. Ga2O3 offers a wider gap and melt-grown substrates, but poor thermal conductivity and the absence of practical p-type doping limit device designs.

Explore wide bandgap materials on LatticeGraph

You can compare computed structures, stability and DFT band gaps for SiC, GaN, AlN and Ga2O3, or browse the nitride semiconductors and wide bandgap oxides classes. For why computed values differ between databases, see our analysis of DFT disagreement.