Thermal-annealing behavior of in-core neutron-irradiated epitaxial 4H-SiC

The effect of thermal annealing on defect recovery of in-core neutron-irradiated 4H-SiC was investigated. Au/SiC Schottky diodes were manufactured using a 4H-SiC epitaxial wafer that was neutronirradiated at the HANARO research reactor. The electrical characteristics of their epitaxial layers were analyzed under various conditions, including different neutron fluences (1.3 x 1017 and 2.7 x 1017 neutrons/cm2) and annealing times (up to 2 h at 1700 degrees C). Capacity-voltage measurements showed high carrier compensation in the neutron-irradiated samples and a recovery tendency that increased with annealing time. The carrier density could be recovered up to 77% of the bare sample. Deep-level-transient spectroscopy revealed intrinsic defects of 4H-SiC with energy levels 0.47 and 0.68 eV below the conduction-band edge, which were significantly increased by in-core neutron irradiation. A previously unknown defect with a high electron-capture cross-section was discovered at 0.36 eV below the conduction-band edge. All defect concentrations decreased with 1700 degrees C annealing; the decrease was faster when the defect level was shallow. (c) 2022 Korean Nuclear Society, Published by Elsevier Korea LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The effect of thermal annealing on defect recovery of neutron-irradiated 4H-SiC was investigated. Electrical characteristics of epitaxial layers were analyzed under different neutron fluences and annealing times. The results showed high carrier compensation in the neutron-irradiated samples, which could be recovered up to 77% with annealing. Intrinsic defects of 4H-SiC and a previously unknown defect were identified, and their concentrations decreased with annealing.