Deep levels induced by reactive ion etching in n- and p-type 4H–SiC

In this study, the authors investigate deep levels, which are induced by reactive ion etching (RIE) of n-type/p-type 4H–SiC, by deep level transient spectroscopy (DLTS). The capacitance of a Schottky contact fabricated on as-etched p-type SiC is abnormally small due to compensation or deactivation of acceptors extending to a depth of ∼14 μm, which is nearly equal to the epilayer thickness. The value of the capacitance can recover to that of a Schottky contact on as-grown samples after annealing at 1000 °C. However, various kinds of defects, IN2 (EC−0.30 eV), EN (EC−1.6 eV), IP1 (EV+0.30 eV), IP2 (EV+0.39 eV), IP4 (HK0: EV+0.72 eV), IP5 (EV+0.85 eV), IP7 (EV+1.3 eV), and EP (EV+1.4 eV), remain at a high concentration (average of total defect concentration in the region ranging from 0.3 μm to 1.0 μm:∼5×1014 cm−3) even after annealing at 1000 °C. The concentration of all these defects generated by RIE, except for the IP4 (HK0) center, remarkably decreases by thermal oxidation. In addition, the HK0 center can also be reduced significantly by a subsequent annealing at 1400 °C in Ar.