Investigation of Vacuum Annealing Temperature Effects on the Microstructure Properties of DC-PECVD Grown Diamond Nanoparticles

In this study, nanodiamonds (NDs) coatings were grown on gold-coated silicon substrates by a DC-plasma enhanced chemical vapor (DC-PECVD) deposition technique using CH4 plus H-2 as the feedstock. The effect of annealing temperature under vacuum environment on the characteristics of the resulting coatings were investigated experimentally by means of Raman spectroscopy, Atomic Force Microscopy (AFM), X-ray diffraction pattern (XRD) and field emission scanning electron microscopy (FE-SEM). Results show that by adjusting annealing temperature up to 200 degrees C, the internal compressive stress, the amount of aromatic ring and the size of the sp(2)-bonded carbon decreases in NDs coatings. It has been found that by further increasing annealing temperature up to 300 degrees C, the degree of graphitization of NDs coatings is increased and graphitic clusters become larger in grain boundaries. In addition, the high concentration and homogenous distribution of particles sizes of the diamond nanocrystals were obtained on the surfaces of the annealed sample at 100 degrees C. Our experimental results can be beneficial guidance to the production of NDs coatings with the desired attributes.