Electron capture and emission properties of interface states in thermally oxidized and NO-annealed SiO2/4H-SiC

Postoxidation annealing in nitric oxide (NO) results in a significant reduction of electronic states at SiO2/4H-SiC interfaces. Measurements of electron trapping dynamics at interface states in both thermally oxidized and NO annealed SiO2/4H-SiC interfaces were performed using constant-capacitance deep level transient spectroscopy (CCDLTS) and double-CCDLTS. We show that the interface state density in as-oxidized samples consists of overlapping distributions of electron traps that have distinctly different capture cross sections. The dominant trap distributions, centered at Ec−0.24 eV with σ∼7×10−19 cm2, and at Ec−0.46 eV with σ∼4×10−17 cm2 are passivated by NO annealing. The remaining interface states all have capture cross sections in the range 10−19−10−21 cm2.