LOCAL HETEROEPITAXY OF DIAMOND ON SILICON(100) - A STUDY OF THE INTERFACE STRUCTURE

An extensive study of the interface between highly oriented chemical v apor deposition diamond films and silicon has been performed using ato mic force microscopy (AFM), high-resolution scanning electron microsco py (HRSEM), x-ray photoelectron diffraction (XPD), and transmission el ectron diffraction. The initial roughness of the silicon substrate has been investigated by AFM. Hydrogen plasma has been found to produce p its on the biased substrate surface. The local order of the beta-SiC g rown on silicon (100) during the bias-enhanced nucleation step has bee n investigated by XPD through the C 1s and the Si 2p intensity modulat ions. Differences in the XPD diffraction features have been studied an d found to be due to the element and energy dependence of the scatteri ng effect. The preferential orientation of the diamond nuclei with res pect to the silicon substrate has been quantified by comparison of HRS EM pictures and XPD patterns. Only 30-40 % of the crystallites have be en found to be oriented relative to the substrate at an early growth s tage of a highly oriented diamond film. The partial heteroepitaxy of t he diamond nuclei has been confirmed by transmission electron microsco py through electron diffraction and bright- and dark-field images: Sim ulations of the XPD patterns induced by tilted and azimuthally rotated diamond crystallites have been performed in order to reproduce the sm eared-out features of the experimental diffractograms. The short-range order of the diamond lattice at this early growth stage has been foun d. 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 o r become diamond nuclei and are etched away by the hydrogen plasma dur ing the growth process.