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18 December 2006


Normally-off GaN power transistor with low on-state resistance

At last week’s International Electron Devices Meeting 2006 in San Francisco, CA, USA, Panasonic (Matsushita Electric Industrial Co Ltd) of Osaka, Japan announced the development of a gallium nitride power transistor with normally-off operation. The firm claims it is the world’s first demonstration of conductivity modulation in GaN as a novel operating principle leading to low on-state resistance. The new transistor enables low-loss and high-voltage power switching devices.

Normally-off operation has been strongly desired for GaN power transistors, but previously reported approaches have resulted in high on-state resistance. In the new ‘gate injection transistor’, a normally-off positive threshold voltage of 1V is achieved by using a pn-junction gate structure instead of a conventional metal gate. In addition, the injection of holes from the p-type gate layer drastically increases the drain current, resulting in a low specific on-state resistance (RonA) of 2.6mΩcm2.

The high breakdown voltage of 640V is obtained on cost-effective silicon substrate. The transistor is applicable to future high-efficiency power switching systems replacing silicon-based power devices, the company claims.

Applications have been filed for 89 domestic and 52 international patents.