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 ∼7× 10-19 cm2, and at Ec -0.46 eV with ∼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.