IEEE Power Electronics Magazine - March 2015 - 47

As a result, it intends to sample 21,700-V Schottky diodes
to select customers in 2015 under a nondisclosure agreement. While SiC modules will continue to move up in voltage and power, there is a necessity to build unique packages
that are suitable for high-frequency applications, stated
Kierstead. Concurrently, Cree is also working on migrating
from 4 to 6-in wafers to cut cost while improving voltage and
current ratings with faster switching properties. Although
6-in power tools are under qualification, the migration will
depend on how fast we grow, noted Kierstead.

High-Temperature Operation
Besides enabling SiC diodes and transistors to tackle higher
breakdown voltages at higher current and higher frequencies, some manufacturers are also pushing the temperature
rating on these devices to take full advantage of the WBG
material. STMicroelctronics, for instance, has fully characterized its 1,200-V SiC MOSFET at 200 °C in a plastic package (Figure 3), which is sampling to customers. "We are the
only supplier of SiC MOSFETs running at 200 °C in a plastic
package," said Salvo Coffa, STMicroelctronics group vice
president for R&D. The work does not stop here. "We are
going to 225 °C and then 250 °C," added Salvo. "This
involves improving the package," continued Salvo. Target
applications for these very high-temperature SiC MOSFETs
are solar inverters and harsh environments like down-hole
oil drilling and geothermal instrumentation.
The company road map shows that 1,700-V MOSFETs
with on-resistance going from 150 mX to 1 X are under
development and slated for release in the first quarter, with
production by the second quarter. Simultaneously, the company will also continue to expand the 1,200-V MOSFET line
with lower and higher on-resistance as well as new packages. A 1,200-V MOSFET at 50 mX is also in the works and
is expected to be launched in the third quarter. In a year
and a half, the plan is to improve the breakdown voltage to
2,200 V and then move upward, stated Filippo Di Giovanni,
unit manager of Advanced Technologies Business. Although
ST today is using 4-in wafers for production, it intends to
migrate to 6-in wafers in the second quarter.
GeneSiC Semiconductor is another supplier exploiting
the properties of SiC for high-temperature applications. The
company has developed SiC junction transistors (SJTs) and
Schottky rectifiers for operation up to 250 °C with low leakage current. However, the high-temperature SJTs are offered
as bare die products for use in high-temperature assemblies
in the 650-1,200-V range. In addition, high-temperature SJTs
and rectifiers are also being offered in high-temperature
discrete hermetic packages. According to the maker, hightemperature 600-V SJTs in the 3-50-A ratings are offered in
JEDEC standard through-hole and surface mount packages.
On the commercial side, GeneSiC took its 1,200- and
1,700-V SJTs to production in early 2013 and has made a
distribution agreement with Digi-Key, said Ranbir Singh,
GeneSiC's president. The company's Schottky rectifiers
have been in production since 2010. In late 2014, the supplier

fig 3 The STMicroelctronics 1,200-V SiC MOSFET is rated at 200 °C
in a plastic package. (Photo courtesy of STMIcroelectronics.)

released a family of low on-resistance (25 mX) 1,700- and
1,200-V SJTs in TO-247 packages. Meanwhile, it has also
released SiC-based ultrahigh-voltage bipolar devices (p-i-n
rectifiers and thyristors) with 6.5-13-kV voltage ratings.
To help engineers evaluate its SJTs, the company has
readied gate driver board and LTSPICE IV models for SJTs.
Using the new gate driver board, power conversion engineers can verify the benefits of sub-15-ns temperatureindependent switching characteristics of SJTs with low
driver power losses. Similarly, incorporating the new SPICE
models, circuit engineers can quickly evaluate the high-efficiency benefits of SJTs.
United Silicon Carbide Inc. (USCi) has released a portfolio of 1,200-V normally on SiC junction FETs in die form
and TO-247 packages with very low on-resistance. Combining these normally on junction gate FETs (JFETs) with a
low-voltage MOSFET in a cascode configuration, USCi has
developed a normally off switch. In addition, it has also
demonstrated SiC JFETs and diodes at 6.5 kV and is in
the process of extending the voltage range of its Schottky
diodes and JFETs to 1,700, 3.3, and 4.5 kV, respectively.
As Tables 1 and 2 show, there are many more manufacturers of WBG power devices expanding their product
portfolios while improving reliability and production availability. As these newer technologies eye applications where
Si is maturing and emerging applications are demanding
new levels of performance beyond Si, the scenario for WBG
power devices looks good. With falling prices, they are
ready to reshape power electronics landscape. A new era in
power electronics has begun.

About the Author
Ashok Bindra (bindra1@verizon.net) is the editor-in-chief
of IEEE Power Electronics Magazine and a veteran writer
and editor with more than 30 years of editorial experience
covering power electronics, analog/RF technologies, and
semiconductors. He has worked for leading electronics trade
publications in the United States, including Electronics,
EETimes, Electronic Design, Power Electronics Technology, and RF Design.
March 2015

z IEEE PowEr ElEctronIcs MagazInE

Table of Contents for the Digital Edition of IEEE Power Electronics Magazine - March 2015