Structural characterization of poly-SiC grown on SiO₂/Si by metalorganic chemical vapor deposition

Polycrystalline β-SiC films were deposited on (100) Si wafers in the temperature range of 950 to 1130°C from a mixture of Si(CH3)4 and H2 in a hot-wall reactor. A thin SiO2 buffer layer was thermally grown on the Si substrate prior to the deposition, in order to avoid strain development due to the 8% difference in thermal expansion coefficients of the substrate and the overgrown. The growth of the β-SiC polycrystalline films occurs by the formation of microtwins having their twin planes perpendicular to the direction of growth. The strong [111] preferred orientation through microtwins at low temperatures (∼1100°C) is attributed to the very low adatom mobility in conjunction with the high number of atoms which can be incorporated per unit area on the (111) plane at low energy sites.