Raman and X-ray studies of polycrystalline CVD diamond films

Abstract

Differently prepared microwave plasma-deposited diamond films with a broad spectrum of morphological and Raman spectroscopic features were investigated by scanning electron microscopy (SEM), Raman spectroscopy and X-ray diffraction (XRD). XRD indicates the presence of graphitic polytypes in most samples, independent of growth conditions or morphology. X-ray texture analysis reveals pronounced fibre textures not only for well-faceted deposits, but also for smooth, fine grain films. Information about internal strain, stacking faults and average crystallite sizes is obtained from diffraction peak shifts and widths. Crystallite sizes deduced from XRD profiles are found to be orders of magnitudes smaller than the grain sizes observed by SEM. An analysis of the diamond Raman peak position, width and shape suggests that Raman peak broadening is dominated by phonon lifetime reduction. Raman and X-ray diffraction data reveal a reciprocal relationship between the width of the diamond Raman line and the crystallite size.