Development of ultra-smooth ballas diamond incorporated nano-composite carbon thin films using PECVD technique

Nanocomposite carbon thin films consisting of diamond and graphite phases were grown on silicon substrates at different self-bias voltages ranging from -100 to -200 V. Plasma enhanced chemical vapor deposition process with acetylene as the precursor gas was used for growing the films. All the films were grown at low temperature and in absence of argon at a partial pressure of 0.02 mbar. The characteristics of the films were studied using FESEM, XRD, Raman spectroscopy, AFM and TEM techniques. The structure and morphology of the film were found to vary with self-bias voltage. The XRD and Raman spectra of the films showed the presence of nanocrystalline diamond and graphitic phases. The microstructural analysis of the films with FESEM revealed the growth of nanocrystalline diamonds as unfaceted ballas/cauliflower shaped and graphite as fine lamellae. The graphitic carbon layers were found to be more at lower self-bias voltages while the diamond nano-clusters were found increasing with self-bias voltages. The TEM results showed 3-4 nm of diamond particles confirming the formation ultra nanocrystalline diamond into the carbon films. The AFM studies had demonstrated that the films developed in the present study has ultra-smooth surface with the surface roughness of 0.39-0.6 nm.