Papers by Keyword: Surfacial Morphology

Abstract: In the present study, Functionally gradient HA-ZrO2-Ti coatings (FGC) on Ti6Al4V were prepared by the plasma spraying process. The residual stress and surfacial morphology of coating were studied by X-ray diffraction and scanning electron microscopy with an energy dispersive spectroscopy. The results showed that: (1) the residual stress of FGC is 72.1Mpa, much lower than that of single HA coating, (2) The surfacial morphology of the FGC showed typical characteristics of plasma-sprayed coating, no microcracks was observed because of its the thermal expansion matched between the gradient coating and substrate.

Abstract: 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 1400°C, 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°C and for that of 1500°C. 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 1550°C. Schottky barrier diodes were fabricated on a non-doped C-face epitaxial layer grown at 1500°C and it was verified that a high quality metal-semiconductor interface was formed on the epitaxial layer.