Raman spectroscopy of thin DLC film deposited by plasma electrolysis process

A thin diamond-like carbon film was deposited on Ni substrate by plasma electrolytic deposition in ethanol-water solution. The thickness of the deposited carbon film was measured about 40–60nm by using glow discharge optical emission spectroscopy and optical profilometer. The characterization of film structure by Raman spectroscopy showed the superposition of Raman features on a photoluminescence background because of low thickness of the deposited film. The surface enhanced Raman scattering technique by coating the carbon film with Au nanoparticles and high power laser in Raman spectroscopy was used as Raman intensity enhancer. Amplified Raman signals by using both techniques showed formation of diamond-like carbon film and various sp2 and sp3-bonded compositions on grain boundaries of nanostructure carbon coating. The Raman spectrum of the Au coated carbon film revealed an additional band at 2150cm−1, which is related to the carbyne structure whereas carbyne band could not be detected using high power laser. Comparison of Raman spectra at two wavelengths of 632.8 and 785nm showed changes in the intensity and position of Raman bands. Likewise, the 785nm laser wavelength excitation has sufficient energy to enhance the scattering from the grain boundary structures. •The thin DLC film was successfully deposited on Ni substrate by the CPE process.•The SERS enhanced Raman revealed D and G bands and an additional band in 2150cm−1•The appearance of carbyne band (2150cm−1) by SERS is due to its low concentration.•High laser power Raman showed D and G bands and two bands in 1130 and 1430cm−1.•The presence of thin DLC film containing sp, sp2 and sp3 carbon bonding was proved.