4.9 kV breakdown voltage vertical GaN p–n junction diodes with high avalanche capability

In order to avoid sudden catastrophic hard breakdown in high breakdown voltage vertical GaN p–n junction diodes, punch-through induced breakdown structures have been newly considered. Mg acceptor concentration in the p-GaN layer was reduced so that the punch-through breakdown occurred before the hard breakdown. By using a wafer with triple drift layers and the p-GaN layer with lowered Mg concentration of 3 × 1017 cm−3 grown on a freestanding n-GaN substrate, the diode showed a high breakdown voltage of 4.9 kV with high reverse avalanche capabilities against sudden increase of reverse current over 5 orders of magnitudes. No degradation was observed after fifteen repetitive measurements.