TEM analysis of planar defects in β-SiC

This paper reports on a transmission electron microscopy (TEM) and high resolution TEM (HRTEM) investigation of the extended defects in β-SiC grown on Si (0 0 1) substrates by CVD. The main defects observed were stacking faults and twins. Stacking fault contrast can be explained by using the dynamical theory of electron diffraction. It was found that in β-SiC, stacking faults on inclined {1 1 1} planes exhibit complementary and symmetrical bright-field and dark-field fringe images. This observation is ascribed to the low anomalous absorption ratio of Bloch waves in SiC. Excellent agreement was found between experimental and simulated inclined stacking fault images in β-SiC. Narrow dark bands on {1 1 1} planes viewed edge-on generated streaks but no additional spots in selected area diffraction patterns. HRTEM revealed that these defects are extrinsic stacking faults. Models for the introduction and evolution of the lattice defects observed will be presented.