By thermal oxidizing 4H-SiC at 1150 to 1300C, the Z1/2 and EH6/7 concentrations could be reduced to below 1011/cm3. However, the oxidation introduced a high concentration of the HK0 center (EV+ 0.78eV). Additional annealing in Ar at 1550C resulted in elimination of the HK0 center. Thus, all of the major deep levels could be eliminated by using the two-step thermal treatment. Based upon the depth profiles of the deep levels, a model was proposed for defect generation and elimination.

Elimination of the Major Deep Levels in n- and p-Type 4H-SiC by Two-Step Thermal Treatment. T.Hiyoshi, T.Kimoto: Applied Physics Express, 2009, 2[9], 091101