Design and fabrication of high current AlGaN/GaN HFET for Gen III solid state transformer

We have successfully designed and fabricated the high current AlGaN/GaN HFET using 4 masks process. We have achieved the maximum on-current of 7.3A at 1.5V with TO-3 power package. Multi-finger cell-design was implemented to achieve high current extraction from specific active area. In addition, the mesa-free design was adopted to reduce the process steps by employing the self-isolation with surrounded Schottky gate. Length of unit finger is 1000um. Total width of multi-finger is 80 mm. The measured Ronsp and breakdown voltage are 3.4mΩ-cm2 and 450V, respectively. Although the designed breakdown voltage (BV) was 600V, BV reduction has been observed after fabrication due to the process variation. However, overall figure of merit of this device is 2 times superior to that of Super Junction Power MOSFET.