Local heteroepitaxy of diamond on silicon (100): A study of the interface structure

An extensive study of the interface between highly oriented chemical vapor deposition diamond films and silicon has been performed using atomic force microscopy (AFM), high-resolution scanning electron microscopy (HRSEM), x-ray photoelectron diffraction (XPD), and transmission electron diffraction. The initial roughness of the silicon substrate has been investigated by AFM. Hydrogen plasma has been found to produce pits on the biased substrate surface. The local order of the beta-SiC grown on silicon (100) during the bias-enhanced nucleation step has been investigated by XPD through the C 1s and the Si 2p intensity modulations. Differences in the XPD diffraction features have been studied and found to be due to the element and energy dependence of the scattering effect. The preferential orientation of the diamond nuclei with respect to the silicon substrate has been quantified by comparison of HRSEM pictures and XPD patterns. Only 30-40 % of the crystallites have been found to be oriented relative to the substrate at an early growth stage of a highly oriented diamond film. The partial heteroepitaxy of the diamond nuclei has been confirmed by transmission electron microscopy through electron diffraction and bright- and dark-field images: Simulations of the XPD patterns induced by tilted and azimuthally rotated diamond crystallites have been performed in order to reproduce the smeared-out features of the experimental diffractograms. The short-range order of the diamond lattice at this early growth stage has been found. The amount of carbon on the silicon substrate has been measured by x-ray photoelectron spectroscopy and HRSEM. Comparing the results, we postulated the existence of carbon domains which are too small to be or become diamond nuclei and are etched away by the hydrogen plasma during the growth process.