Causes of Leakage Current in Vertical GaN P–N Diode under Reverse Bias

Dislocations have traditionally been investigated as the primary cause of leakage current in GaN power devices, similar to the other semiconductor materials. However, advancements in GaN substrate technology have significantly reduced dislocation densities. Recent studies have correlated leakage current and surface roughness in p–n diodes (PNDs), prompting further research into surface roughness effects. In this study, the additional causes of the leakage current in GaN PNDs are investigated beyond dislocations. Vertical PNDs are fabricated on GaN substrates and the reverse I – V curves are categorized into three leakage types: low‐leakage, high‐leakage, and breakdown. The primary focus was on high‐leakage pNDs, whose leakage currents increase even when the carrier concentration is distributed in the n‐GaN layer on the order of 10 15–16 cm −3 . These findings highlight the critical importance of suppressing the nonuniform distribution of carrier concentration in the n‐GaN layer, especially when targeting higher breakdown voltages to minimize leakage currents.