High Voltage Vertical GaN-on-GaN Schottky Barrier Diode with High Energy Fluorine Ion Implantation Based on Space Charge Induced Field Modulation (SCIFM) Effect

Electric field crowding at the Schottky edge and Schottky barrier lowering induced leakage current are two major problems that limit the performance of GaN-on-GaN vertical SBD. In this paper, we try to solve these issues. On one hand, a planar edge termination method based on high-energy fluorine ion implantation is explored for high voltage vertical GaN SBD. The space charge induced field modulation effect (SCIFM) is discovered in the ion implanted region. The electrons injected in the implanted region could effectively reduce the surface electric field, alleviating the field crowding at the metal edge. The SBD terminated with high-energy fluorine implanted region presents a breakdown voltage of 1300 V. Utilizing the depletion effect of space charges, the leaky path through the implanted region is partially blocked by the high-energy fluorine ion implanted guard rings. The reverse leakage current of SBD with guard rings is reduced by nearly 3 orders at the reverse bias of 300 V without the deterioration of forward characteristics. On the other hand, the fluorine ion implantation based quasi-JBS structure is investigated to shield the electric field seen by the Schottky contact and reduce the Schottky barrier lowering induced leakage current. The turn-on voltage modulation effect and improved breakdown voltage are observed in the fabricated quasi-JBS diodes, confirming the validity of the SCIFM mechanism in the ion implanted region.