IEEE Power Electronics Magazine - June 2018 - 46

3) vertical GaN materials and devices (cochairs to be
determined)
4) emerging UWBG materials and devices (cochairs to
be determined).
Given that the first two categories are much more
mature than the latter two, and are now finding their way
into applications, the focus at present is on them. Future
activity will focus on the latter two subworking groups as
those technologies mature. Descriptions of the first two
subworking groups follow.

SiC Materials and Devices Subworking Group
The SiC materials and devices subworking group (SiCMDWG) of the ITRW is composed of members from industry and academia with specialization in SiC materials and
devices. The progress in material development has had a
significant impact on the roadmap for SiC devices. In addition, the device roadmap is based on application needs and
is essential to coordinate with application groups. The goals
of the SiC-MDWG are threefold. First, it aims to identify key
applications that will experience game-changing performance by adopting the appropriate SiC technology in large
volume. Second, based on the specific applications identified, it will highlight the device criteria that manufacturers
should target so the benefits of SiC components are fully
realized in these design spaces. Third, for the long-term
development in SiC devices, it will define devices that do
not yet exist and will create a roadmap of what needs to be
worked on to realize these devices. To accomplish these
tasks, the team identified SiC experts to provide feedback
and establish the desired characteristics of SiC components
utilized in these areas. A time line has been established to
complete the first iteration, with results to follow at a conference later this year.
To facilitate the roadmap-building process, a template
has been created to standardize the data collected for
the roadmap. First, the team is documenting SiC power
devices at a high level. This includes desired device types
[e.g., MOSFET, JFET, IGBT, gate turn-off thyristor, and so
on] and applications, operation conditions, and required
voltage and current ratings in the short term (approximately five years), medium term (approximately ten years),
and long term (approximately 15 years). The cost target in
US$/A is key for SiC devices to be widely adopted in power
systems and is emphasized in this section.
With the general specifications of the devices fully
defined, the template turns its attention to the preferred
power device parameters, including dynamic characteristics, gate charge, and reverse-diode characteristics.
The purpose is to collect data on the following important device characteristics for each application in various years of development: gate driver design, maximum
gate-source voltage and threshold voltage, and capacitive values including input, output, and Miller capacitances. A few key parameters such as turn-on and turnoff losses and Coss stored energy are included to quantify

IEEE PowEr ElEctronIcs MagazInE

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the switching losses in hard- and resonant-switching
conditions, respectively. Device data on figures of merit
[(FOMs) e.g., RDS_ON versus QG], body diode characteristics, and fault-tolerance capabilities (e.g., short-circuit
protection time) are also collected in this section.
Since the progress in SiC materials, including substrates and epitaxy, will largely determine device cost and,
ultimately, performance, it is critical to gather this material information for the roadmap. This is done in the "SiC
Material Parameters" section of the template. The data
collected includes the wafer area, major killer defects,
percentage of defect-free wafer area, minority-carrier lifetime, and so on, specified for short-, medium-, and longterm time frames.
At the end of the template, a short questionnaire is
included (shown in "SiC Questionnaire") to gather additional information about the use of devices in their
intended applications. Suggestions and comments on the
benefits of using SiC devices in various applications, cost
considerations, desired packages and modules, major
barriers preventing SiC devices from gaining widespread
adoption, reliability status, and so on are requested. Along
with these details, the roadmap will estimate points in
time when SiC devices will reach cost parity with their Sibased counterparts.

Lateral GaN Materials and
Devices Subworking Group
The lateral GaN materials and devices subworking group
(L-GaN-MDWG) of the ITRW covers a similar scope as
the SiC-MDWG described previously, but with a focus on
lateral GaN power devices, such as AlGaN/GaN high-electron mobility transistors (HEMTs). Such devices are
expected to play a major role in future power electronics
due to their superior intrinsic material properties as compared with the current silicon-based power devices. GaNbased radio-frequency (RF) devices have already demonstrated commercial success valued at more than
US$100 million, and while GaN power device research and
development efforts have nearly reached their 15-year mark,
revenue forecasts have decreased over the last few years as
shown in Figure 1, signaling a slower market penetration
than what was originally projected. However, the fundamentals of the value proposition remain the same, and
industry is moving forward with development efforts supported by the emergence of several key industry-wide
efforts that will help to shape a path forward with a good
level of convergence, one of which is ITRW, while another
is an effort from the Joint Electron Device Engineering
Council concerning the standardization of reliability testing, qualification, parametric testing, and datasheets. These
efforts will contribute to the widespread adoption of
emerging GaN power electronics technologies.
This IEEE ITRW effort will address the GaN HEMT
device roadmap in close collaboration with the GaN
applications working group as well as the SiC-MDWG

Table of Contents for the Digital Edition of IEEE Power Electronics Magazine - June 2018