Infrared Raman study of the phonon linewidth and the nondiamond carbon phase in 〈110〉 and 〈100〉 textured polycrystalline diamond films

Abstract

Raman spectroscopy has been used to study the width of the 1332 cm -1 phonon line and the relative intensity of scattering from nondiamond carbon in 〈110〉 and 〈100〉 textured diamond films prepared by low pressure chemical vapor deposition. Infrared excitation at 1.16 eV has been used to give a high sensitivity to amorphous graphitelike carbon inclusions in diamond films. For 〈110〉 textured films a narrowing of the phonon linewidth is observed with decreasing intensity of scattering from amorphous carbon. Films with vanishing Raman scattering from nondiamond carbon, even under infrared excitation, exhibit the narrowest phonon linewidth of about 4 cm-1. For 〈100〉 textured films also a comparatively narrow phonon linewidth is observed in spite of the strong Raman signal from nondiamond carbon. This can be explained by defective growth sectors terminated by {111} facets which surround the almost perfect 〈100〉 columns.