High breakdown GaN HEMT with overlapping gate structure

GaN high electron mobility transistors (HEMTs) were fabricated using an overlapping-gate technique in which the drain-side edge of the metal gate overlaps on a high breakdown and high dielectric constant dielectric. The overlapping structure reduces the electric field at the drain-side gate edge, thus increasing the breakdown of the device. A record-high three-terminal breakdown figure of 570 V was achieved on a HEMT with a gate-drain spacing of 13 μm. The source-drain saturation current was 500 mA/mm and the extrinsic transconductance 150 mS/mm.