By Tomas Moreno, Corporate Development, Dialog Semiconductor
GaN’s Time in the Spotlight
Has Finally Arrived
Switching to Gallium Nitride over silicon offers improved power density and higher efficiency at a lower cost.
The emergence of wide bandgap semiconductors for power conversion is an important turning point for
AC/DC and DC/DC applications in consumer, enterprise,
automotive, and clean energy systems. Gallium Nitride
(GaN) in particular, enables the world’s fastest power
switches, making it possible for power supplies to deliver
a much higher efficiency and superior power density. This
new technology also provides a much better use case in
the consumer adapter area—faster charging and smaller
form factor. It can also provide much a lower cost of
ownership for server applications, thanks to less wasted
energy and lower cooling costs.
GaN high-electron mobility transistors (HEMT) are a
high-performance alternative to superjunction MOSFETs.
They deliver superior switching performance due to
their low gate charge, “flat” output capacitance, and zero
reverse recovery. This translates into a power device
that allows higher energy efficiency, while enabling new
topologies. GaN devices are capable of operating several
orders of magnitude higher than their silicon counterparts,
and have the potential to be manufactured at a lower cost
None of this is really new, per se. GaN didn’t just
break out onto the power conductor scene overnight.
It has been available for well over a decade now, used
across compound semiconductor manufacturers, research
institutions, and a myriad of small wafer fabs. Today,
it has been widely adopted for use in various LED and
RF applications. However, GaN has never really been
considered mainstream before—largely because of these
preconceived notions of GaN being a very exotic process,
held back by a combination of high manufacturing costs
and track record of subpar reliability.
However, over the last five years, we’ve seen GaN
take significant strides on both device and process
improvements, creating a baseline standard of quality
and reliability that is friendlier to mass production and
adoption. In fact, many of the biggest foundries across the
planet either currently have, or are ramping up, their GaN
While cost impediments are nothing new for emerging
hardware electronic technologies, a path to adoption—
The two major cost contributors to GaN are the wafer
substrate and subsequent epitaxial deposition processing
costs. However, we see three areas that counterbalance
and allow for decrease costs:
1) Lower processing costs due to improvements in
epitaxial growth (MOCVD) throughput from better
manufacturing efficiencies and lower capital expenditures
from older and partly depreciated equipment.
2) A GaN HEMT device has a much smaller effective
area per Rdson (or higher overall current capability per
device area) compared to an equivalent superjunction
MOSFET, resulting in higher device density per wafer.
3) GaN HEMTs as lateral devices make monolithic
integration of multiple devices easier and more cost-effective than superjunction vertical devices—yielding
a smaller total solution and a lower cost bill of material
One of the challenges for engineering teams to use GaN
HEMTs has been the small number of complementary
drivers and controllers available in the market. GaN has
a tighter requirement to drive the gate, given its unique
structure. Therefore, a tuned (or optimized) driver is
needed to enable faster switching using GaN.
In addition to drivers, new controllers implementing
zero-voltage switching (ZVS) topologies are needed to
extract the value of GaN. ZVS controllers enable much
smaller magnetic components by increasing switching
frequency, while saving energy and reducing heat.
Superjunction MOSFETs generally fall short of ZVS
due to their non-linear output capacitance. GaN enables
these new ZVS topologies due to its relatively linear
output capacitance. When deploying ZVS topologies,
additional savings in BOM costs may be obtained by
integrating passive components and reducing the size
and cost of magnetic components. Recently, a number
of these new GaN-friendly controllers have been
introduced to the market.
An important application where GaN delivers superior