Emerging wide-bandgap (WBG) semiconductors hold the potential to revolutionize the
electronics world, promising to advance the global industry in much the same way as the
invention of the silicon (Si) chip over 50 years ago enabled the modern computer era.
The electronic bandgap is what allows semiconductor devices to switch currents on and
off to achieve a desired electrical function, and WBG materials, the category of
electronic materials in which the bandgap energy exceeds approximately 2 electronvolts
(eV), exhibit characteristics and processes that make them superior to Si for many
applications. The most mature and developed WBG materials to date are silicon carbide
(SiC) and gallium nitride (GaN), which possess bandgaps of 3.3 eV and 3.4 eV
respectively, whereas Si has a bandgap of 1.1eV. SiC and GaN devices are starting to
become more commercially available. Smaller, faster, and more efficient than counterpart
Si-based components, these WBG devices also offer greater expected reliability in
tougher operating conditions.
Enabling High Power, High Temperature Electronics
Advantages of WBG semiconductors over Si in power electronics include lower losses for
higher efficiency, higher switching frequencies for more compact designs, higher
operating temperature (far beyond 150° C, the approximate maximum of Si), robustness in
harsh environments, and high breakdown voltages. Diverse applications range from
industrial functions, such as motor drives and power supplies, to automotive and
transportation systems including hybrid and electric vehicles, aircraft, ships, and
traction, to wireless communications, military systems, space programs, and clean energy
generation from solar inverters and wind turbines.
Advancing the Optoelectronics and Lighting Industries
A characteristic of WBG materials is the ability to emit light in the visible
spectrum. This has allowed innovation in the solid-state lighting industry, where
developments in WBG-based light emitting diodes (LEDs) have resulted in devices with
greater lighting efficiency and much longer lifetimes than incandescent bulbs. In
fact, LEDs provide light output on the order 160 lumens per watt, with a service
life between 35,000 to 50,000 hours, while incandescent lights provide less than 20
lumens per watt and last between 1,000 to 2,000 hours. WBG technology is also used
in laser diodes, with next generation DVD players, including Blu-ray and HD DVD
formats, employing GaN-based blue lasers.
SiC, GaN, and Consumer Applications
SiC is by far the most mature WBG technology, attributable in part to its excellent
thermal conductivity. Due to SiC’s ability to effectively transfer generated heat
away from itself, SiC is especially well suited for the highest power applications
such as photovoltaic systems and wind turbines, as well as high temperature
operating environments like down-hole drilling where temperatures can exceed 200° C.
GaN is popular as a more cost-effective alternative to SiC, but given that today’s
GaN is bonded over a Si or SiC substrate as opposed to grown on a bulk-GaN substrate
for cost reasons, GaN is not as thermally conductive as SiC or even standard Si. The
WBG benefits of GaN, such as high voltage operation, high switching frequencies, and
outstanding reliability - coupled with expectations that GaN will reach price parity
with Si equivalents by 2015, keep it as a front-running choice for power electronics
up to 900 V, as well as a superb choice for next generation consumer electronics,
where size, efficiency, and price greatly matter.
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