4H-SiC Epitaxial Growth on Carbon-Face Substrates with Reduced Surface Roughness

4H-SiC epitaxial layers on Carbon-face (C-face) substrates were grown by a low-pressure hot-wall type chemical vapor deposition system. The C-face substrates were prepared by fine mechanical polishing using diamond abrasives with the grit size of 0.25 %m and in-situ HCl etching at 1400ºC, which produced surface roughness of 0.27 nm. The use of the smooth substrates made it possible to decrease the substrate temperature and specular surface morphologies were realized at C/Si ratios of 1.5 or less both for a substrate temperature of 1550ºC and for that of 1500ºC. Surface roughness of 0.26 nm and the residual donor concentration of 6.7×1014 cm-3 were obtained for a C-face epitaxial layer grown at a C/Si ratio of 1.5 and at a substrate temperature of 1550ºC. Schottky barrier diodes were fabricated on a non-doped C-face epitaxial layer grown at 1500ºC and it was verified that a high quality metal-semiconductor interface was formed on the epitaxial layer.