Origin of Giant Step Bunching on 4H-SiC (0001) Surfaces

To elucidate the origin of giant step bunching on 4˚ off-axis 4H-SiC (0001) faces, we carried out hydrogen etching and epitaxial growth under various conditions. We found that giant step bunching occurs during hydrogen etching and epitaxial growth at extremely low or high C/Si ratios, i.e., with an excessive supply of SiH4 or C3H8. From these results, we have proposed that the origins of giant step bunching are asymmetry in the step kinetics in etching and Si or C cluster generation on terraces during growth.