LOCALIZED EPITAXY OF DIAMOND ON (100) SILICON

Diamond films exhibiting contiguous epitaxial crystallites (approximat ely 3-4 mum) have been grown on single crystal (100) silicon by 2.45 G Hz microwave plasma deposition. The diamond films were deposited by a three-step process. In the initial stage the silicon wafer was pretrea ted for 3 h in a 1.8% methane in hydrogen plasma at low pressure. The subsequent nucleation stage was performed, under identical processing conditions, except that a dc bias of -340 V was applied for 25 min. Du ring this period the current increased from 38 mA at the start to 102 mA at the end of the bias. The final growth stage was performed, with an earthed substrate, utilizing a carbon monoxide/methane/hydrogen gas mixture whose composition is conductive to uniformly faceted (100) di amond growth. Scanning electron micrographs showed that a large fracti on of the (100) faces of the diamond crystallites are aligned with the (100) plane of the underlying silicon lattice with the crystallite ed ges parallel to the (110) direction. Raman scattering was used to conf irm this finding by measuring the angular dependence of the Raman back scattering intensity at 1332 cm-1 using plane polarized excitation of individual crystallites within the diamond films.