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SiC Drives Innovation in Power Applications
By Stefano Lovati
ver the past four decades, power devices based on silicon technology have made significant progress, thanks to the adoption of better design and manu-
facturing processes, as well as the availability of high-quality materials. However, most commercial power devices are now approaching the theoretical performance limits imposed by silicon, especially in terms of their ability to block high volt- ages, offer low voltage drop in the “on” state, and switch at very high frequencies. For several years, many research- ers and companies specializing in electronics design have focused their efforts on the search for alternatives to silicon in order to meet the efficiency, reliability, and cost require- ments of the latest-generation power applications.
Silicon carbide is a wide-bandgap material that offers superior electrical and physical characteristics required to far exceed the performance offered by silicon in power applications. As shown in Figure 1, a higher energy band- gap makes WBG materials superior to silicon for power- conversion applications. WBG-based devices such as SiC tol- erate much higher operating temperatures with smaller size than silicon-based equivalents.
GeneSiC Semiconductor, a company founded and chaired by Ranbir Singh, began developing SiC power device technolo- gies several years ago, becoming a pioneer and world leader in the field with 26 granted U.S. patents. The SiC device tech- nology offered by GeneSiC plays a key role in achieving high levels of efficiency in numerous power applications, such as the automotive, smart grid, industrial, aerospace and defense, oil and gas, renewable energy, medical, and trans- portation sectors.
“GeneSiC was founded in 2004 and was soon issued its first patents on silicon carbide devices,” said Singh. “Even though a lot of our funding came from the U.S. government for next-generation, innovative SiC technology develop- ment, we don’t want to be viewed solely as a niche player. ... We offer a comprehensive portfolio with over 100 silicon carbide products.”
SiC benefits
As a WBG semiconductor, SiC exhibits a larger bandgap energy than silicon (3.2 eV, about 3× higher than that of sili- con’s 1.1 eV). Because more energy is required to excite a valence electron in the conductive band of the semiconduc- tor, higher breakdown voltages, higher efficiency, and better thermal stability at high temperatures can be achieved.
The main advantage of a SiC MOSFET is the low drain-source on-resistance (RDS(on)), up to 300× to 400× lower than that of silicon devices at the same breakdown voltage. Therefore, SiC-based power devices can provide higher power levels and thus minimize power losses, improve efficiency, and reduce component footprint. SiC-based devices offer both high electrothermal conductivity and extremely high switch- ing speeds. Low output capacitance and low RDS(on) make SiC devices suitable for switching designs such as power sup- plies, three-phase inverters, amplifiers, and voltage convert- ers (AC/DC and DC/DC). The use of SiC devices also allows significant cost savings and a reduction in the size of the magnetic components (transformers, inductors) used in many switching applications.
O
Energy Bandgap in Materials
overlap
Bandgap
Insulator
Semiconductor
Conductor
FIGURE 1: ENERGY BANDGAP COMPARISON AMONG DIFFERENT MATERIALS (SOURCE: MOUSER ELECTRONICS)
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ASPENCORE GUIDE TO SILICON CARBIDE
Electron energy