Term · General Industry
Wide bandgap
A class of semiconductors with bandgaps well above silicon's, chiefly silicon carbide and gallium nitride. The wider gap supports higher voltage, junction temperature and switching frequency, which is why these materials dominate new power electronics designs.
- Also known as
- WBG
- Type
- Term
- Domain
- General Industry, Device physics
Notes
Electric vehicle traction inverters were the volume application that finally made silicon carbide economics work.
Overview
Wide bandgap (WBG) describes semiconductors whose bandgap, the energy needed to free an electron to conduct, is well above silicon's, with silicon carbide (SiC) and gallium nitride (GaN) the two in volume use. Because they withstand higher electric fields and temperatures, they let power devices block more voltage, switch faster and waste less energy than silicon parts of the same size. The term is used mostly in power electronics and RF, though the same materials also give blue, green and ultraviolet LEDs and lasers.
How it works
The bandgap reflects how tightly a material holds its electrons. With a wider gap, a much larger electric field is needed before carriers are knocked loose and the material breaks down, and the material keeps behaving as a semiconductor at higher temperatures. In practice this lets a WBG device block high voltage in a compact structure and run hot with less loss than silicon. Silicon carbide has a bandgap of about 2.3 to 3.3 eV, depending on its crystal form, and GaN about 3.4 eV.
The two materials have settled into different roles. SiC is used mainly for high-voltage, high-temperature work, for example in electric vehicles and industrial equipment. GaN transistors, often grown as thin layers on silicon wafers, switch very fast: Texas Instruments cites switching frequencies above 500 kHz, which shrinks the transformers and inductors around them, so GaN suits compact adapters and server power supplies. GaN is also used in microwave power amplifiers.
The trade-offs are cost and engineering effort. Making WBG devices cost-competitive with silicon is still a stated aim of industry programmes such as PowerAmerica, and very fast switching puts extra demands on gate drivers, packaging and board layout. Materials with still wider gaps, such as aluminium nitride and diamond, are also used or studied, for example aluminium nitride in short-wavelength ultraviolet LEDs.
Examples
- Infineon's CoolSiC silicon carbide and CoolGaN gallium nitride device families, offered alongside its silicon parts.
- Texas Instruments GaN power stages with integrated gate drivers for servers, laptop adapters and on-board chargers for electric vehicles.
- PowerAmerica, founded in 2015 by the US Department of Energy as a Manufacturing USA institute to speed commercial use of SiC and GaN power devices.
- Gallium nitride blue LEDs and laser diodes, which depend on GaN's wide, direct bandgap.
Why it matters
Related terms
Part of the General Industry glossary, with every term in the topic and the lifecycles, tools and standards that use them.
Where it appears on the Hub
Used on 8 pages of the Hub. In each group, the pages that mention it most come first.
Lifecycle stages and gates
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