Investigation of field emission characteristics and microstructure of nickel-doped DLC nanocomposite films by electrochemical deposition

The as-obtained nickel doped DLC films by the electrochemical process demonstrated the surface morphology of a nano-tip transformed to bumps with increasing nickel compound concentration in the electrolyte, simultaneously the sp2-C content greatly increased. Nickel was incorporated into highly cross-linked amorphous carbon matrix, forming the typical nanocrystalline/amorphous composite microstructure, which was in the form of element nickel, nickel hydroxide, and nickel oxide. Field emission performance showed that nickel incorporation effectively lowers the threshold field from 9.9 to 8.4 V/μm at the electron emission current density of 1 μA/cm2, and greatly increased the emission current density from 21.88 to 163.89 μA/cm2 under 12.455 V/μm for DLC film. The Raman and XPS measurements of the as-deposited films suggested that spatially localized conduction channels formed by the graphite-like sp2-carbon and metallic particles might be responsible for the electron emission in nickel-doped DLC films.