COMPARATIVE-STUDY OF MICROCRYSTALLINE DIAMOND

Raman spectra of diamond powders and polycrystalline CVD diamond films with diamond crystalline size from 4 mu m to 5 nm have been measured as a function of the crystallite size. The Raman diamond line at 1332 cm(-1) was found for the powder to become more asymmetric with decreas ing particle size to 5 nm. A strong influence of substrate temperature and methane-hydrogen gas mixture pressure during diamond films growth by the d.c. glow discharge method on linewidths and peak position hav e been found. The observed results are explained by ''phonon confineme nt'' and by strain effects. CVD and laser-evaporated nanophase diamond films were produced and have shown a Raman line at 1140 cm(-1).