Correlation Between Reverse Leakage Current and Electric Field Spreading in GaN Vertical SBD With High-Energy Ion Implanted Guard Rings

This work focuses on the bias-dependent reverse leakage current and carrier depletion process of vertical gallium nitride (GaN)-on-GaN Schottky barrier diodes (SBDs) with fluorine ion-implanted guard rings (GRs). The reverse leakage characteristics in the vertical GaN SBD with GRs sequentially go through ohmic conduction, thermionic field emission (TFE), and space charge limited conduction (SCLC) model as the reverse bias increases gradually. Once the traps in the implanted termination region are fully ionized, the device will undergo large leakage current at high biases. Compared with infinite area ion implanted edge termination (ET), ion-implanted GR can effectively reduce the leakage current at low biases. In addition, there are kinks in the reverse current-voltage curves, which proved to be related to the electric field spreading effect of individual GR. Based on the analysis of reverse leakage current, the electric field modulation mechanism of ion-implanted GRs is reviewed.