Deep Levels Generated by Thermal Oxidation in n-Type 4H-SiC

The Z 1/2 center ($E_{\text{C}} - 0.67$ eV), which is a lifetime killer in n-type 4H-SiC epilayers, is reduced by thermal oxidation. The oxidation, however, simultaneously generates other deep levels: ON1 ($E_{\text{C}} - 0.84$ eV) and ON2 ($E_{\text{C}} - 1.1$ eV) centers. From the behaviors (generation condition, thermal stability, and change in the depth profiles) of the ON1 and ON2 centers in samples (i) oxidized in O 2 , (ii) implanted with C + or Si + atoms, and (iii) oxidized in N 2 O (or NO), we suggest that these defects may originate from the same defect in different charge states, related to both carbon interstitials and N atoms.