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

The effect of thermal annealing on defect recovery of in-core neutron-irradiated 4HSiC was investigated. Au/SiC Schottky diodes were manufactured using a 4HSiC epitaxial wafer that was neutron-irradiated at the HANARO research reactor. The electrical characteristics of their epitaxial layers were analyzed under various conditions, including different neutron fluences (1.3 × 1017 and 2.7 × 1017 neutrons/cm2) and annealing times (up to 2 h at 1700 °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 4HSiC 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 °C annealing; the decrease was faster when the defect level was shallow.