Reduction of defect states in atomic-layered HfO₂ film on SiC substrate using post-nitridation annealing

The changes of the defect states below the conduction band in atomic-layered HfO₂ film grown on SiC substrate were examined as a function of the post-nitridation annealing temperature in an NH₃ ambient. As the post-nitridation annealing temperature increased up to 600 °C, the incorporated nitrogen into the HfO₂/SiC interface was gradually increased. The band gap and valence band offset were mostly increased as a function of the post-nitridation annealing temperature and the band alignment of HfO₂ films changed. O K-edge absorption features revealed two distinct band edge states below the conduction band edge in HfO₂ films, and these defect states were dramatically reduced with increasing of the post-nitridation annealing temperature. The reduction of defect states in HfO₂/SiC improved the electrical properties such as the leakage current density, breakdown voltage, and trap charge density in the HfO₂ film and interface of HfO₂/SiC.