Nickel concentration dependent structural and optical properties of electrodeposited diamond like carbon thin films

Abstract

Diamond like carbon (DLC) and composite nickel incorporated diamond-like carbon (Ni-DLC) films have been synthesized on ITO coated glass substrates using low voltage electrodeposition method. Modifications of structural and optical properties of thin films have been investigated with varying Ni concentration. Average grain size of Ni-DLC granules is found to decrease with increasing molarity of Ni in electrolytic solution. XRD pattern depicts multi-phase nature of Ni-DLC film. Incorporation of Ni nanoparticles in DLC matrix has been confirmed by TEM. Interestingly optical bandgap energy decreases from 2.31 to 1.58 eV with decrease in nickel content in the electrolytic bath. Simultaneously Urbach energy exhibits an increasing trend from 1.972 to 2.374 eV. Presence of sp2 and sp3 bonded carbons has been indicated by FTIR spectra. The number of sp2 bonding in carbon matrix is enhanced with dilution of electrolyte. The peaks in the range of ~600–750 cm−1 in Ni-DLC films have been attributed to metal incorporation into DLC matrix. Study reveals that the bandgap and the particle size of carbon nanocomposite films can be tailored by controlling the amount of nickel in the electrolyte.