On barrier-free vertical GaN PN junction diode enabled by ion-implantation and ex-situ Mg diffusion process

This letter reports the application of ex-situ thermal diffusion of metallic Mg into GaN in mitigating the Schottky barrier that may arise underneath the standard Ni/Au contact to Mg ion implanted GaN. The GaN PN junction diode realized after the Mg ion-implantation process resulted in a Schottky barrier in the p-side of the diode, in close agreement with the previous report. However, the diode that had an ex-situ thermal diffusion of Mg process after ion-implantation process showed dramatic increase in the forward current without introducing compromise in the reverse breakdown voltage.