The initial homoepitaxial growth behavior on nearly on-axis 4H-SiC substrates was
investigated. We have observed circular etch pits on the surface of on-axis substrate in the presence of
source gases. However, there were no circular etch pits on the surface of off-axis substrates. In
addition, the surface etched by H2 gas did not show circular etch pits even on nearly on-axis substrates.
The shape of the circular etch pits was similar to spiral one. The initial growth behavior of epilayers
was also investigated with various C/Si ratios of source gases (0.6