Reducing the reverse leakage current of AlGaN/GaN heterostructures via low-fluence neutron irradiation

Abstract

Reduction of the reverse leakage current is critical to AlGaN/GaN heterostructures in high power and high frequency applications. Taking AlGaN/GaN Schottky barrier diodes (SBDs) as an example, we demonstrate both theoretically and experimentally that low-fluence neutron irradiation can be a promising way to reduce the reverse leakage current while maintaining other electronic properties almost unchanged. A clear physical picture is given to elucidate the mechanism, which includes three main scenarios: (i) in pre-irradiated AlGaN/GaN heterostructures grown by metal organic chemical vapor deposition (MOCVD) on sapphire substrates, the configuration of threading dislocations (DLs) is the mixture of pure DLs and DLs decorated by group-III vacancies (VIII-DLs); (ii) neutron scattered group-III interstitials are mobile and prone to passivate VIII-DLs, changing the configuration of DLs to monomorphic pure DLs; (iii) after the saturation of the passivation, neutron scattered group-III interstitials begin to escape from the system. The physical analysis is consistent with the trends in the experimental data. Our work provides a new post-processing treatment for reducing the reverse leakage current of AlGaN/GaN heterostructures grown by MOCVD on sapphire substrates.