Study On The Deposition Technology Of The DLC Films And LSPR Interface Formed By DLC Films Coated On The Surface Of Au And Ag Nanoparticles

Diamond-like carbon (DLC) films were deposited on the biological substrates by the self-made radio-frequency magnetron plasma enhanced chemical vapor deposition (RF magnetron PECVD) device in this paper. The probe profilometer, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), the friction-wear spectrometer, UV-Vis spectrophotometer and the scratch tester were used to characterized the thickness, structure and morphology, fiction and the optical properties of the films as well as the film-substrate adherence. The preparation technology and growth mechanism of the DLC films were discussed. Annealing treatment under different temperatures had been taken to analyze the thermal stability of the DLC films. Besides, the gradient RF power was adopted to synthesize the DLC films on various substrates to check the influence of substrates on the films’structure and properties. The LSPR interface was formed by depositing the DLC films on the surface of Au or Ag nanoparticles with appropriate preparation parameters. The influence of DLC films on LSPR absorption spectra of the nanoparticles was studied.The result of film thickness test by probe profilometer showed that DLC films’ thicknesses were influenced by the RF power, deposition time and the reaction gas flux. The deposition efficiency of butane was higher than that of acetylene. The film thickness was positively correlated with the RF power and the thickness could reach up to454.27nm under720W. The larger the gas flux was, the thicker the DLC films were. A linear relation between the film thickness and deposition time was found so it was convenient to obtain the DLC film with desired thickness by adjusting deposition time. The observation of AFM and FESEM morphology revealed that the DLC films were composed of spherical carbon particles which were uniformly distributed so the film surface was dense and smooth. No obvious defects were seen so the film roughness was low. There would be localized segregation of the carbon particles with the increase of RF power. Raman spectra showed that it was the typical diamond-like carbon film. The content of sp3hybridized bonds in the DLC films was high that the largest could reach up to76.90%demonstrated by XPS. There would be higher sp3bonds by increasing the RF power and reducing deposition time. Therefore, the DLC films exhibited good friction performance. The friction curves showed that the process was stable with the lower friction coefficient which would decrease the wear rate of the substrates. It was necessary to check the adherence between DLC films and substrates by the scratch tester as large inner stress was existed inside the films which severely limited the use of the films. The result indicated that there was better adhesive performance when the RF power was665W and the gas flux was1.5sccm. High absorption at the light band of about300nm by the DLC films was found. The transmissivity of the film increased with increasing the wavelength which would be over95%above600nm at the visible and near infrared region. The variation of film structure and morphology happened at the higher annealing temperature which was identified as graphitization.The LSPR interface was made by depositing the DLC films on the surface of the Au or Ag nanoparticles. The Au nanoparticles prepared by thermal evaporation had regular shape and its LSPR absorption peak located in555nm. Intensity of the Au absorption peak increased apparently after coated by DLC films and a dramatic oscillatory behavior of the absorption peak shift with the film deposition time was shown. The Au or Ag nanoparticles synthesized by electrochemical deposition were sparsely distributed and partial agglomeration would be seen. Similar influences of the DLC films on their LSPR absorption spectra appeared. Certain chemical modification to the LSPR interface was carried out. The test of LSPR signals after the linkage of the biological molecules to the interface showed that the DLC film was too thick to obtain the signals. As a result, the thickness of the DLC films on the LSPR interface should be limited within50nm.