POWER ELECTRONICS FEATURE GaNingPOWER: A MATERIAL SCIENCE
Jim Witham, CEO at GaN Systems looks towards a new era in power electronics with Gallium Nitride (GaN) power switching semiconductors and the significant benefits of this
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ower systems need to be more efficient to reduce our impact on the
planet and smaller, lighter and less expensive to enable technological advances to continue to improve human life. Over the past decades, great improvements have been made by MOSFET and IGBT manufacturers, but further advances are obtaining diminishing returns and a new material system is needed. Silicon carbide (SiC) has better physical properties for power than silicon but is very expensive, and its properties are not as good as gallium nitride. GaN material offers orders of magnitude improvement in switching and conduction performance and, when produced on GaN-on-Silicon substrates, can reduce power system costs. Only diamond power semiconductors have been proposed as a superior material system to GaN, but the consensus is that we are decades away from commercial viability. In speed, temperature and power handling, gallium nitride is now set to take over - power system engineers around the world concur that the availability of GaN transistors may be the single most important advance since the IGBT became available in the 1990s. The excitement about GaN for power
applications stems from its unique material and electronic properties, which result in products with power losses cut 50-90 percent; system size and weight reductions of up to 75 percent and a decreased Bill-of-Materials cost. This will alter the way power systems are designed and used – a golden age of new power products is imminent. GaN devices offer five key characteristics
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which are due to the inherent properties of gallium nitride: high dielectric strength, high operating temperature, high current density, very high speed switching and low on-resistance. Compared to silicon, GaN offers ten times higher electrical breakdown characteristics, three times the bandgap and exceptional mobility, so it’s clear that the development of devices that can make the best use of these inherent characteristics while offering ease of adoption into applications will offer significant commercial advantage. Key application areas for gallium nitride
power transistors include mains AC/DC power supplies, DC/AC inverters, DC/DC power supplies, datacomms, consumer goods, motors, pumps, induction heating,
Island Technology die – GaN Systems’
battery chargers, solar power, wind power, electric and hybrid vehicles, and many other automotive and transportation applications.
MAKING GaN TECHNOLOGY ACCESSIBLE AND EASIER TO ADOPT Today, GaN transistors with the right performance parameters, reliability and cost are coming on the market and enabling this transition to begin.
Figure1:
The GS66506P GaN transistor range from GaN Systems
Figure 2:
Switching loss comparison of the GS66506P
semiconductor die are built as an array of alternating ‘islands’ of drain and source material, with the gate as a grid between the islands. This maximises the amount of gate length in a given area, and spreads the heat from the channel evenly over the device. This leads to substantial advantage of reduction in the size and cost of gallium nitride devices. The islands are not connected to one another within the die – instead, the current is taken vertically off the die in post-processing or in the package. GaNPX packaging – It is not enough to
For example, Ottawa-based company
GaN Systems’ range of GaN power transistors has current ratings from 8A to 250A and the devices’ unique structure maximises wafer yields and produces highly- efficient power switching transistors at significantly lower cost than traditional design approaches. GaN Systems’ core IP is its Island Technology die design, GaNPX packaging technology and Drive Assist on- chip drivers. It’s worth taking a closer look at each of these in order to understand how the properties of gallium nitride have been maximised?
/ ELECTRONICS “GaN material offers major improvement in
switching and conduction performance and when
just make the best die. In order to take advantage of the Island Technology devices’ intrinsic fast switching and dense current carrying capability, the company has designed proprietary packaging, GaNPX, which has minimal inductance and superior thermal resistance. The packages have no wire bonds which aid in limiting inductance as well as eliminating a common reliability issue with semiconductor devices. Drive Assist on-chip drivers – GaN Systems uses on-chip drivers which simplify circuit design and solve the drive issues while improving the switching speed. The design improves the noise immunity allowing GaN Systems to deliver a wide range of 100 - 400A monolithic, normally-off GaN transistors. Overall, these three technologies mean that GaN Systems’ products use standard, off-the-shelf driver electronics and address reliability and performance issues such as electro-migration and debiasing. In addition, its technology enables GaN Systems to scale the die for significantly higher current than other topologies, with high yield, and to support a range of foundry processes, device ratings and substrate technologies with a single family of designs. Clearly adopting new
produced on GaN-on-Silicon substrates, can reduce power system costs . . .”
technologies is a learning curve and it is incumbent on device manufacturers to ease the path of engineers looking to build these new gallium nitride devices into their latest designs.
GaN Systems
www.gansystems.com +1 613-686-1996
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