Study on the Impact of Mg-Channeled Implantation on Junction Termination Extension for GaN Vertical Power Devices Using TCAD Simulation

This study investigates the influence of different magnesium (Mg) ion implantation techniques on the performance of gallium nitride (GaN)-based junction termination extension (JTE) structures. To this end, we perform a systematic TCAD simulation study on JTE structures using two different implantation techniques of Mg ions: 1) channeled implantation and 2) random (conventional) implantation. We perform channeled and random Mg ion implantations and subsequent activation annealing to GaN epitaxial layers to obtain actual Mg depth profiles experimentally. We used the obtained profiles for the TCAD simulations. The Mg-channeled implanted JTE structure exhibits a significantly larger optimal JTE dose window compared to the Mg-random implanted JTE structure. This is because, in the JTE structure with a channeled Mg depth profile, the electric field crowding is more suppressed than in the JTE structure with a random Mg depth profile. These results indicate that deep-graded Mg depth profiles are more suitable for the relaxation of electric field strength concentrations than shallower profiles. In addition, we found that the Mg-channeling-based JTE structure was more advantageous than the Mg-random-based JTE structure that considers the interface charge at the passivation SiO2/GaN interface.