3 kV Monolithic Bidirectional GaN HEMT on Sapphire

TL;DR

This paper reports the first demonstration of monolithic bidirectional GaN HEMTs exceeding 3 kV breakdown voltage, with optimized design achieving high performance suitable for advanced power converters.

Contribution

It introduces a novel monolithic bidirectional GaN HEMT with over 3 kV breakdown voltage and optimized field plate design, advancing power device technology.

Findings

Breakdown voltage >3 kV achieved in monolithic bidirectional GaN HEMTs.

Optimized field plate geometry improves breakdown voltage.

Device exhibits steep subthreshold swing and high on/off ratio.

Abstract

More than 3 kV breakdown voltage was demonstrated in monolithic bidirectional GaN HEMTs for the first time having potential applications in 1200V or 1700V-class novel power converters. The on resistance of the fabricated transistors was ~20 ohm.mm or ~11 mili ohm.cm^2. Breakdown voltage was optimized by utilizing two field plates in either side of the transistor and optimizing their geometry. Shorter first field plate lengths (less than 2 micron) resulted in higher breakdown voltage and the possible reason for this was discussed. The transistors had a steep subthreshold swing of 92 mV / dec. The on/off ratio was greater than 10^5 and it was limited by the tool capacity. The fabricated 3 kV transistor was benchmarked against the state-of-the-art monolithic bidirectional GaN HEMTs in the performance matrices of breakdown voltage and on resistance, that showed crucial progress.