Exploring Surface and Bulk Defect States for High-Power Vertical GaN Diodes with Mg Implantation
Abstract
The objective of this proposal is to investigate the role of surface and bulk states in the performance vertical GaN diodes. By forming an understanding of these states, high power GaN diodes will be demonstrated that are capable of meeting the Navy#s needs for its next generation Power Electronic Power Distribution System (PEPDS). The integrated Power Electronics Building Block (iPEBB) needsto be both highly efficient and compact. GaN offers a >2.5-fold performance advantage over incumbent SiC and a pathway to reduced conduction losses and higher switching speeds that will translate to simplified thermal heatsinking requirements and miniaturized passives, all of which would reduce the size and weight of future iPEBB#s.Despite its great promise, surface and bulk defects present in GaN limit its high-power handling capability. Moreover, efficient ion implantation remains a key technological challenge in III-Nitrides, and must be addressed in order for vertical GaN-based power devices to meet their full potential. This technology will be used to realize kV-class gallium nitride (GaN) junction barrier Schottky (JBS) diodes. Until now, GaN JBS diodes fabricated using Mgimplantation have been limited to less than 800 V, which is not sufficient to realize even the minimum PEBB1000 unit. A major reason behind this is the low Mg activation efficiency and incomplete damage recovery obtainable by traditional post-implantation annealing techniques. The PI was the first to use ultra-high pressure annealing (UHPA) in tandem with Mg implantation to demonstrate a vertical GaN PN diode; this study unveiled that significant Mg diffusion can occur as a result of annealing. Moreover, it was found thatcontacts to both implanted and masked regions were non-ideal. These effects call for a fundamental study of the phenomena at play in this material.In this context, surface and bulk defects will be thoroughly studied in the proposed project. This will be executed by leveraging UHPA to efficiently activate implanted Mg in GaN, but also to manipulate and probe surface and bulk defects. The proposed tasks are summarized as follows: (1) Study the impact of annealing conditions on surface oxide constructions and contact behavior, (2) Study the electrical activation of bulk defects via annealing and its impact on device scaling, (3) Study the depth-dependentactivation of implanted Mg following drive-in diffusion, (4) Harness UHPA-induced carrier activation and diffusion to demonstrate low-loss kV-class GaN JBS diodes. All in all, the proposed program seeks to establish a fundamental understanding of how nitride surface and bulk defects impact electrical performance, and how efficient ion implantation technologies can be used to manufacture high voltage III-Nitride power devices capable of improving the efficiency and portability of shipboard power distributions systems. Moreover, it will position the PI as a leading power device researcher, and generate opportunities for long-lasting collaboration with NRL throughout the PI#s academic career.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 24, 2023
- Source ID
- N000142312638
Entities
People
- Spyridon Pavlidis
Organizations
- North Carolina State University
- Office of Naval Research
- United States Navy