Elimination of the Major Deep Levels in n- and p-Type 4H-SiC by Two-Step Thermal Treatment

By thermal oxidation of 4H-SiC at 1150–1300 °C, the Z1/2 and EH6/7 concentrations can be reduced to below 1×1011 cm-3. By the oxidation, however, a high concentration of HK0 center (EV + 0.78 eV) is generated. Additional annealing in Ar at 1550 °C results in elimination of the HK0 center. Thus, all the major deep levels can be eliminated by the two-step thermal treatment. Based on the depth profiles of deep levels, a model for the defect generation and elimination is proposed. The carrier lifetime in 4H-SiC epilayers has been improved from 0.64 (as-grown) to 4.52 µs by this method.