Effects of nitridation for SiO2/SiC interface on defect properties near the conduction band edge

Abstract

We have investigated the effects of NO annealing on the electrical properties of a SiO2/4H-SiC interface. The electrical properties of the NO-annealed sample are different from those of the wet-annealed sample. NO or wet annealing generates positive or negative charges, respectively, in the insulator. The interface trap density (Dit) near the conduction band edge (Ec − 0.1 eV, where Ec is the conduction band edge) increases with NO annealing. In contrast, the Dit of the NO-annealed sample at around Ec − 0.2 eV is lower than that of the wet-annealed sample. The interface state near the conduction band edge in the NO-annealed sample is identified to be of the donor type. Thus, it is considered that the higher Dit near the conduction band edge and/or Coulomb scattering due to positive charges causes a decrease in the n-channel mobility in the nitrided SiO2/SiC interface by NO annealing.