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

摘要

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 μm and in-situ HCl etching at 1400℃, 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 1550℃ and for that of 1500℃. Surface roughness of 0.26 nm and the residual donor concentration of 6.7x10~(14) 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 1550℃. Schottky barrier diodes were fabricated on a non-doped C-face epitaxial layer grown at 1500℃ and it was verified that a high quality metal-semiconductor interface was formed on the epitaxial layer.