Comparative Study of Defects in 4H-SiC Epilayers Grown on 4[degrees] Off-Axis (0001) and (000-1) Substrates

In this paper, we present a comparison of defects in 4H-SiC epilayers grown on 4[degrees] off-axis (0001) and (000-1) substrates. It was confirmed using high sensitive surface observation and micro-Raman spectroscopy that the generation of epitaxial defects on (000-1) C-face substrates was less susceptible to substrate morphological defects such as pits than that on (0001) Si-face substrates and 'comet-like' defects on (000-1) C-faces were caused by the inclusion of 3C-SiC. Moreover, PL imaging observation showed that stacking fault densities decreased when increasing the growth temperature, and they increased when increasing the C/Si ratio, irrespective of the face polarity. The densities, however, were lower for C-faces at higher growth temperature and C/Si ratio. The present results indicated that C-faces were preferable to Si-faces to achieve smooth step-flow growth suppressing epitaxial defects and stacking faults, which were influenced by the substrate morphological defects and the fluctuation of C/Si ratio in the epitaxial growth.