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Fuji Electric and Furukawa Partner on GaN Power Devices

Fuji Electric and Furukawa Electric Co. have formed a research association for cooperative research and joint development of GaN-on-Si-based (gallium nitride on silicon) wide bandgap power devices which can be used in more efficient and capable power electronics for hybrid and electric drive vehicles, among other applications. Fuji Electric produces power devices for hybrids and has also been working on GaN; Furukawa Electric has GaN technology.

Currently, Silicon insulated gate bipolar transistors (Si-IGBTs) are widely used ininverters for hybrids. However, devices with higher performance characteristics—including higher operating temperatures, lower resistance, and higher breakdown voltages—are required for powre electronics for future electric drive vehicles.

The potential of GaN for higher voltage, next-generation power devices has been widely recognized and researched over the past 10 years or so. Toyota, for example, began working on vertical device structure power switching devices using GaN substrates several years ago in its central R&D Lab using GaN substrates from several providers.

In a paper presented in May at the CS Mantech (Compound Semiconductor Manufacturing Technology) conference, Tsutomu Uesugi and Tetsu Kachi from Toyota noted that:

...performance of the GaN power device has been progressing rapidly. To overtake existing power devices, total progress of technologies for GaN power devices, such as GaN substrates, processing and device design, has to be accelerated.

The Fuji Electric and Furukawa partnership has three initial goals:

  • Development of MOSFET and SBD (Schottky barrier diode) using GaN on Si substrates. The focus is on the epitaxial crystal growth technique used, with an improvement in quality control in the buffer layer deposition conditions on the substrate (crystal defects and stress reduction).
  • To examine the device structure of the result, and to evaluate the reliability the structure and implementation from the perspective of the power device implementation.
  • To perform a market survey of power semiconductor devices based on GaN SBD and MOSFET and the features of the existing Si and SiC devices.

Development targets include:

  • FY 2009: 600V voltage SBD prototype; principles and prototyping of the MOSFET structure.
  • FY 2010: Manufacturing samples of GaN SBD and MOSFET with optimized structure .
  • FY 2011: Production of engineering samples.

The partners forsee an initial first year investment of ¥8 billion (US$83 million).



Henry Gibson

Silicon carbide is another semiconductor that can run hot. Diodes are available. Transistors have been tested.
One company has modified a car with hydraulic systems and improved the efficiency by 100 %. That is twice the mileage per gallon. There is no need for small improvements yet when buyers are buying horse-power not transportation or piston count not fuel efficiency. Adequate transportation for most cities can be had with a single piston engine. A two piston TZERO drove across the US at maximum freeway speeds when traffic allowed.



Manufacturing large diameter single crystal wafers for growing epitaxial layers in silicon carbide is not trivial.

This capability would be needed if such devices were ever to replace the silicon waffers now generally in use.


Manufacturing silicon carbide wafers is also extremely energy intensive, more so than silicon. This is because of the much higher temperature required during zone purification of ingots. Also, there is currently no source of larger size SiC wafers necessary for more cost-effective device manufacturing.

I don't know how much energy is required to create and purify raw GaN material, but I do know that gallium is far less plentiful than most materials. It could be used to make extremely efficient photovoltaic cells, but I was told by a semiconductor physicist that there isn't enough of it available on the earth's crust to support mass production as currently envisioned. Using it for super efficient power switching devices and LEDs is probably a much better use for it.

International Rectifier has recently developed smaller GaN switching MOSFETs,
so IGBTs are a logical next step.

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