Synthesis of nanocrystalline diamonds by microwave plasma

Abstract

Nanocrystalline diamonds, varying in size from 40 to 400 nm, with random faceting were grown without the help of initial nucleation sites on nickel substrates as seen by scanning electron micrographs. These carbonaceous films were deposited in a microwave plasma reactor using hexane/nitrogen based chemical vapour deposition. The substrate temperatures during deposition were varied from 400 to 600 °C. The morphological investigations obtained by scanning electron micrographs and atomic force microscopy revealed the presence of nanocrystallites with multifaceted structures. Micro Raman investigations were carried out on the deposited films, which conclusively inferred that the growth of nanodiamond crystallites seen in the scanning electron micrographs correlate with clear Raman peaks appearing at 1120 and 1140 cm−1. Nanoindentation analysis with atomic force microscopy has revealed that the carbonaceous deposition identified by the Raman line at ~1140 cm−1, in fact, is related to nanodiamond on account of its hardness which was ~30 GPa. X-ray diffraction data supported this fact.