AlGaN/GaN Heterostructure Filed Effect Transistors (HFETs) are promising fast high-power switches for the next generation of energy converters. The present work focused on the challenge of AlGaN/GaN power switch development which lies in achieving both low dynamic ON-resistance and high breakdown voltages simultaneously in a device.

The present work shows the importance of parasitic air breakdown in limiting breakdown voltages of these devices at around 450 V and presents novel ways to achieve breakdown voltages as high as 1600 V with specific ON-resistance as low as 3.4 mΩ.cm². These values are among the best reported so far.

Silicon dioxide encapsulation, Silicon Nitride passivation and Field plating of AlGaN/GaN HFETs was found to be a comprehensive design approach to have low ON-resistance high voltage III-Nitride switching devices working in air ambience for power converter applications. The AlGaN/GaN HFET device rise time was measured to be 10 ns and fall time was 30 ns. These results prove the feasibility of using high voltage III-Nitride HFETs as low loss ultra-fast power converter switches.

A novel approach to achieving Bidirectional Power Switching functionality using AlGaN/GaN HFETs will be discussed and for the first time experimental data showing power bidirectional capability of these devices will be presented.