Structure and morphology of c-SiC films obtained by acetylene reaction with Si(111) surface

Abstract

In this work we investigated the structure and morphology of silicon carbide films grown under ultra-high-vacuum (UHV) conditions by acetylene (C 2H 2) carbonization of Si(111) surfaces kept at 650 °C. We used several UHV electron techniques to probe the local structural properties of the film and scanning tunneling microscopy (STM) to study its morphology. Our results indicated that C atoms occupy tetrahedral substitutional sites in the Si with a C–Si bond of 1.90±0.03 Å as in a bulk cubic SiC (c-SiC) crystal. X-ray diffraction data confirmed the formation of highly (111) oriented epitaxial crystallites characterized by the c-SiC lattice. STM images showed the formation of ordered, interconnected structures, rather flat at the atomic scale, triangular in shape, characterized by the same orientation and with an average area of 5000 nm 2 and an average height of 10–15 Å. Only a few holes can be detected which may be interpreted as empty spaces left by the patchwork growth of the silicon carbide triangular islands. Therefore, our growth procedure resulted to produce crystalline c-SiC films by using one of the most lowest temperature reported in literature.