Page 6 - PowerUp 2021 Conference Proceedings for PEN

WIDE BANDGAP

SiC Power Technology

Status and Barriers to

Mass Commercialization

By Victor Veliadis, professor of electrical and computer engineering at North
Carolina State University and executive director and CTO of PowerAmerica

Silicon (Si) power devices have dominated power electronics due to their low-cost volume
production, excellent starting material quality, ease of fabrication, and proven reliability. Although
Si power devices continue to improve, they are approaching their operational limits primarily due
to their relatively low bandgap, critical electric field, and thermal conductivity that result in high
conduction and switching losses, as well as poor high-temperature performance. Silicon carbide’s
(SiC’s) large bandgap and critical electric field allow for high-voltage devices with thinner layers,

which lowers resistance and associated conduction and switching losses. Combined with SiC’s large
thermal conductivity, high-temperature operation at high power levels is possible with simplified
thermal management. Furthermore, thinner device layers and low specific on-resistance allow for
a smaller form factor that reduces capacitance. This enables efficient operation at frequencies well
above those of silicon, which minimizes the size of passive system components. Thus, the SiC-
based system is more efficient, lighter, has smaller volume, and is cost-competitive (despite the
higher-than-Si device cost), as bulky magnetics and heatsinks are minimized.

These compelling efficiency and system benefits have led to significant development efforts over

the last two decades, as SiC planar and trench MOSFETs and JFETs are commercially available
from several vendors as discrete components and high-power modules in the 650- to 1,700-V
voltage range. Presently, power-electronic engineers can select Si, SiC, and gallium nitride (GaN)
components for use in their systems. There are, of course, numerous tradeoffs when selecting the
right material device for an application and voltage: Current, frequency, efficiency, temperature,
and cost are important considerations.

Voltage ranges in which Si, SiC, and GaN
are particularly competitive are shown in
Figure 1. Si is reliable, rugged, cheap, and
capable of high-current efficient operation
at “lower” frequencies. It is particularly
competitive in the 15- to 650-V range. GaN
offers efficient high-frequency operation Figure 1: Voltage ranges in which Si, SiC, and GaN are
at a reasonable cost, as it is fabricated in competitive

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