Design and Fabrication of Vertical GaN p-n Diode With Step-Etched Triple-Zone Junction Termination Extension

We demonstrate edge termination for vertical GaN p-n diodes using step-etched triple-zone junction termination extension (JTE). The technique was found to yield high breakdown efficiency without degradation of forward characteristics. The electric field distribution at various JTE thicknesses was simulated, and the experimental results were well matched to the simulation results. The fabricated GaN p-n diode with step-etched triple-zone JTE shows a breakdown voltage of 550 V corresponding to a junction termination efficiency of 75%, with a turn-on voltage of 3.1 V, a specific ON-resistance of 1.3 $\text{m}\Omega \cdot $ cm2, and leakage current at −200 V of 80 nA/cm2. The multistep JTE strategy demonstration could be important for future applications for multikilovolt-class GaN vertical power devices.