Radiation Effects in N-Face and Nonpolar m-Plane III-Nitrides and Heterostructures

High voltage, high power semiconductor devices are becoming ubiquitous in both civilian and military applications where exposure to radiation may occur. The need for power electronics that can survive in harsh radiation environments is driving research into alternatives to conventional silicon and existing wide-band-gap semiconductors such as SiC and Ga-face GaN. Among these materials, GaN has emerged as an attractive option due to its wide band gap, high breakdown voltage, and high-temperature stability. While GaN possesses some degree of intrinsic radiation hardness due to its strong bonding, it remains susceptible to performance degradation from radiation damage. Recently, N-face and nonpolar m-plane GaN have received attention for their potential to enable faster, higher-power, and normally-off power devices. However, very little research has been conducted on the radiation tolerance of these alternative orientations of GaN. Compared to conventional Ga-face devices, the different polarization induced charges, dislocation densities, and layer orders present in N-face and nonpolar mplane devices may result in different performance impacts upon irradiation. The proposed research seeks to improve the fundamental understanding of the effects of radiation interactions in semiconductors, semiconductor defects, and device physics through direct experimentation with Nface and nonpolar m-plane GaN-based structures. The response of four different structures, Schottky and pn diodes, heterostructures and superlattices, from each of the material types will be considered. The sample response to different doses will be quantified through characterization measurements before, during, and after irradiation. The effects of radiation energy on the damage produced will also be studied with the use of several different energy sources. This basic research project will yield the knowledge and data necessary to design the next generation of high-performance, radiation-tolerant devices. The proposed fundamental science, conducted in an academic setting and with guidance and resources from Pacific Northwest National Laboratory, will be pivotal in training the next generation of scientists and engineers