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New Sumitomo SiC power transistor

Sumitomo Electric has developed a new silicon carbide (SiC) power transistor which achieves low on-state resistance, high stability and other excellent performance characteristics that are suited for for electric vehicles (EV)/hybrid electric vehicles (HEV), solar power conditioners and other applications.

With the increasing need for energy efficiency, reducing power conversion loss is strongly required of power semiconductors. Compared with widely-utilized silicon (Si)in power devices, SiC has a higher blocking voltage and lower on-state resistance. Since these features enable dramatic reduction of the power loss of electric power apparatuses, SiC is seen as a next-generation power semiconductor. On the other hand, SiC is a compound semiconductor and its crystal defect poses a reliability-related problem.

Sumitomo’s new SiC transistor is a V-groove metal oxide semiconductor field effect transistor (VMOSFET) that uses a particular plane orientation (0-33-8) for the channel that turns on/off the flow of electrons, enabling the formation of an oxide film interface with relatively low defects compared to a normal orientation (0001).

As a result, the new transistor can achieve a blocking voltage of 1,200 V and a remarkably low on-state resistance of 2.0 mΩcm2. The low-defect performance of this transistor also significantly stabilizes the threshold voltage fluctuation (at 0.12 V or less at 175 ˚C for 1,000 h) that has prevented the practical use of SiC transistors.

Cross-sectional view of the VMOSFET.
Click to enlarge.
  Efficiency characteristics of solar power conditioner.
Click to enlarge.

Due to these advantages, the new SiC transistor is suitable for use in automotive electronic devices demand for which is expected to increase in future. For photovoltaic and other regenerative energy generation system applications, the new transistor was installed in the solar power conditioner that is being developed by Sumitomo Electric's Power System R&D Center and has demonstrated the highest level of efficiency (97.6%) in the industry.

Sumitomo Electric prototyped the new transistor chip of 3 mm square, by epitaxial growth on a 6-inch substrate. The company will use the preproduction line of the Tsukuba Power Electronics Constellations (TPEC) operated by the National Institute of Advanced Industrial Science and Technology to establish a mass-production technology for a new business.



With almost 1.5% gain in efficiency plus other advantages, these devices will soon contribute to extending the range of future BEVs.


So, .09 cm² means an on-state resistance of about 22mΩ.  Figuring a supply at 600 volts, moving 20 kW requires 33 amps for a voltage drop of 7.3 volts and dissipation of about 240 watts.  Meh, better use two in parallel.

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