Ion Implantation-Based Edge Termination to Improve III-N APD Reliability and Performance

We report on the development of ion implantation-based contact-edge termination technique to improve the reliability and performance of p-i-n and p-i-n-i-n GaN ultraviolet avalanche photodiode structures. The GaN photodiode structures were grown on sapphire substrates and implanted along the edge of the p-contact. The implanted devices show an absence of premature breakdown and demonstrate a lower dark-current with reliable ultraviolet photoresponse, compared with the standard unimplanted devices. Device simulations of the implanted structures at the breakdown voltage, show a reduction in crowding and spiking of the electric field along the perimeter of the contact by a factor of $\sim 7$ , compared with the unimplanted structures.