28 April 2010


Acreo and DENSO to co-develop SiC power switches for non-automotive applications

Microelectronics and optics research institute Acreo AB of Kista, Sweden has signed an agreement with DENSO Corp of Kariya, Aichi prefecture, Japan to develop highly efficient, normally-off power switch technology, developed at DENSO, and to evaluate it in non-automotive applications.

Fabricated using silicon carbide (SiC), the design of the switches is based on the material and processing technology available from both parties. DENSO is a diversified supplier of technology, systems and components with 120,000 staff in 34 countries and annual sales of US$32bn, but has been developing high-quality SiC wafer material, power switches and module technology for more than 10 years. Acreo has just 140 employees but has more than 15 years experience of developing epitaxial growth technologies and device processes for SiC.

The initial device to be designed and fabricated is a power switch with an operating voltage of 1200V and a current rating of 50A. The device of choice is an all-epitaxial normally-off junction field effect transistor (JFET), designed and tested at DENSO for current ratings over 50A and with epitaxial material supplied by Acreo.

For the 50A-rated devices, JFET process technology will be established at Acreo’s SiC process line at the ElectrumLab in Kista, and device fabrication will start in autumn 2010. It is planned that packaged JFET devices will be ready for system evaluation demonstrator circuits at the start of 2011. The targeted applications are dc–dc converters, battery chargers, and photovoltaic systems. The technology could be considered for robust high-temperature automotive applications in the future.

The collaboration with DENSO is the result of joint research activities regarding SiC material technology for more than five years. The new agreement includes the transfer of the DENSO JFET technology to Acreo and is supported by the Swedish Governmental Agency for Innovation Systems (VINNOVA) and the Invest in Sweden Agency (ISA), Japan.

Combining both parties’ competences and experience in SiC R&D, material technology and power device design and processing should enable the fabrication of high-performance and efficient normally-off SiC-JFET devices, say the firms, adding that the SiC-JFETs should help to revolutionize power electronics and lead to smaller, lighter and more-efficient power systems. Compared to conventional silicon technology, a reduction in size and weight by at least a factor of six is within reach, with no compromise in energy conversion efficiency.

“The agreement takes our cooperation into a new important phase, enabling us to test the new technology in real, demanding applications,” says Acreo’s CEO Mårten Armgarth. The next generation of power devices are hence directly accessible to Swedish systems firms, he adds.

“It’s time to explore the energy-efficient SiC power device potential for non-automotive applications,” says Hikaru Sugi, DENSO’s senior managing director overseeing its Engineering Research & Development Center.

Search: Acreo DENSO SiC power switches SiC wafers JFETs