DIAMOND HOMOEPITAXY BY CHEMICAL-VAPOR-DEPOSITION

Gem-quality single crystals of diamond were grown by homoepitaxy using microwave plasma assisted chemical vapor deposition. Raman spectra of the (001) films show very low background and the narrowest width at half maximum of the 1332 cm-1 peak was 1.7 cm-1. A prism crystal 1.2 mm high was grown in the [110] direction at 1200-degrees-C and 1% CH4 in H-2. Its Raman peak has a width of 2.7 cm-1. Homoepitaxy is a tool used to study growth processes by analyzing the geometrical details of surfaces morphologies. Growth steps on the (001) surface develop in the [110] directions while triangular plates appear on the (111) surface. The (110) atomic plane does not appear in the [110] growth direction with microfaceted (111) and (111BAR) planes present instead. Crystal structure of diamond grown on the (001), (111), (110) substrates, as well as growth sectors developed in conjunction with this epitaxy, were studied by X-ray diffraction techniques: Laue, oscillation and rotation methods. Atomic force microscopy reached atomic resolution on the (001) surface. The presence of a 2.12 angstrom reflection demonstrates distortion of cubic symmetry and deformation of carbon tetrahedra in the case of (111) epitaxy. In the [110] growth sector a polytype/superstructure network with periodicity three times larger than that of the cubic form was determined. In general it is possible to form tetrahedral carbons with the sequence of tetrahedra different from that of cubic and hexagonal diamonds.