Fundamentals of Silicon Carbide Technology

5.3 Point Defects in SiC

5.3.1 Major Deep Levels in SiC

5.3.1.1 Intrinsic Defects

The major deep levels that are observed in as-grown n-type and p-type 4H-SiC epitaxial layers are mostly intrinsic defects, and their energy positions in the bandgap are as shown in Figure 4.33. Among them, the [152] and EH6/7 [153] centers are the dominant thermally stable defects that are most commonly observed with the highest concentration in all as-grown epitaxial layers. These levels are also dominant in ion-implanted, plasma-etched, or particle-irradiated SiC, as described in Chapter 6. Although a few hole traps, which may originate from the intrinsic defects, are observed, such as HK4 (or P1) [154], they can be annealed out at 1450–1550 °C. Thus, the and EH6/7 centers are the most common and important deep levels in SiC. Note that the signals from the EH6 and EH7 centers usually overlap severely in normal DLTS spectra, and these two defect levels are thus often treated as the single EH6/7 center, ...