OPTICAL REFLECTION AND ANGLE-RESOLVED LIGHT-SCATTERING FROM TEXTURED POLYCRYSTALLINE DIAMOND FILMS

We report on the growth and characterization of polycrystalline diamond films exhibiting fibre textures with the fibre axis parallel [100] or slightly off [100]. The film surface is formed dominantly by almost parallel {100} facets with a minor content of {111} facets. The films were deposited on Si substrates in a ''downstream'' microwave apparatus from H-2-CH4 mixtures with substrate temperatures between 750 and 1000-degrees-C. The surface morphology of the samples was characterized by angle-resolved light scattering. Intensity variations of the scattered He-Ne laser light could be monitored, over 11 orders of magnitude. The [100]-textured films exhibit a strong specular reflection, indicating the optical smoothness of the film surface. The far-field intensity of the backscattered light has been calculated as a superposition of the diffracted-field contributions of the ensemble of surface facets. From the angular dependence of the scattered light we deduce information about the size and orientational distribution of the surface facets. Furthermore, it is possible to determine the surface roughness of the films. The surface morphological data are compared with structural data obtained by X-ray texture analysis.