Mechanisms of CVD diamond nucleation and growth on mechanically scratched Si(100) surfaces

The diamond nucleation has been studied on scratched Si(100) both by surfac e analyses (XPS, AES, ELS) and microstructural probes (AFM, SEM). Two pathw ays for diamond formation and growth are detected: A seeding pathway occurs by direct growth from part of diamond seeds left by the mechanical pretrea tment. Not all of these seeds however are prone to diamond growth as they c an be either dissolved or carburized. A nucleation pathway occurs through a stepwise process including the formation of extrinsic (pretreatment) or in trinsic (in situ) nucleation sites, followed by formation of carbon-based p recursors. It is believed that nucleation sites could be either grooves of scratching lines or protrusions produced by etching-redeposition. The size of these protrusions is not larger than 100 nm. On top of these protrusions as well as on the bare substrate, a thin layer of silicon carbide rapidly forms and DLC carbon likely. This complex process on top of protrusions may constitute carbon-based embryos for fur ther diamond nucleation.