Normally-off GaN Transistors for Power Switching Applications
ECS Trans., vol. 58, no. 4, 145-154 (2013).
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Normally-off high voltage GaN-HFETs for switching applications are presented. Normally-off operation with threshold voltages of more than 1 V and 6 V gate swing has been obtained by using ptype GaN as gate. Different (Al)GaN-based buffer compositions using intentional doping and potential barriers have been used to obtain high blocking voltages. 1000 V blocking was obtained for devices with carbon-doped buffer structures, however, they suffer from a stronger increased dynamic on-state resistance as compared to devices based on an iron-doped GaN-buffer or an AlGaN-buffer. The best trade-off between low dispersion and high blocking strength was obtained for a modified carbon-doped GaN-buffer that showed only a 2.6x increase of the dynamic on-state resistance for 500 V switching.
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany