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

The diamond nucleation and growth processes on a scratched and a virgin Si(100) surface were studied by both electron spectroscopies (XPS) and microstructural probes (SEM, TEM) in order to connect the nature of surface species with the structural changes. We have shown that a preliminary scratching of the substrate surface hugely enhances the nucleation kinetics relative to the virgin sample. This is explained by the much faster formation of stable diamond nuclei in correspondence of suitable nucleation sites. The results have been modeled, considering the covered surface S as the unique parameter. S obeys an Avrami plot of the form S = 1 - exp (-kt(n)) where the exponent n approximate to 2.5 +/- 0.4 over a wide range of deposition is indicative of a constant linear growth rate with decreasing nucleation rate.