The relationship between surface structures and incorporation mechanism of in-situ aluminum (Al) doped p-type 4H-SiC epilayers grown by hot-wall chemical vapor deposition (CVD) has been investigated. Trimethylaluminum (TMA) involving aluminum was used as a dopant source. A mirror-like epitaxial surface without step bunching was obtained for both (0001) Si- and (000-1) C-faces in the range of aluminum concentration below mid 10(17)cm(-3). On the other hand, with the increase of TMA flow rate, an aluminum doped epilayer over 10(19)cm(-3) was grown and step bunching consisting the (0001) terrace and zigzag steps was observed for the (0001) Si-face. For the (000-1) C-face, saturation tendency of aluminum concentration around mid 10(17)cm(-3) was shown, and extremely smooth surface regions and islands with the streamline shape along off direction are observed.