The outstanding question from our previous study is why r-B4C grows epitaxially on the Cface but not on the Si-face. From that study and the results presented here, we conclude that r-B4C nucleates and grows on both faces of 4H-SiC, but on the C-face, it grows epitaxially and grows to less than half the thickness compared to the polycrystalline r-B4C film growth on the Si-face. The surface morphologies are accordingly different for the two 4H-SiC faces (Fig. ). HRTEM in Fig. and stacked-EELS spectra in Fig. results reveal that these differences cannot be explained by SiC surface roughness (Fig. ) or from the presence of interlayers (Fig.