CHARACTERIZATION OF DIAMOND-LIKE CARBON BY RAMAN-SPECTROSCOPY, XPS AND OPTICAL-CONSTANTS

Crystalline diamond coatings and, increasingly, diamond-like amorphous carbon (DLC) films are used for tribological and protective layers fo r their hardness and chemical inertness. They are also under investiga tion for their electron emitting properties, with possible application s in field emission displays. In this study, hydrogen-free DLC films w ere deposited by laser ablation using a KrF excimer laser and fluences between 0.5 and 2 J/cm(2). Information about the disorder and short r ange order in the films was gained via Raman spectra. As the ratio of graphitic and diamond bonds (sp(2) and sp(3)) is often hidden in these measurements, other analytical methods have to be included. XPS spect ra exhibit for certain films the presence of sp(3) bonds or graphitic growth. For a better determination of the sp(3)-content, a correlation with optical properties in the near TR to near UV region was establis hed. These values depended strongly on the substrate temperature and t he laser fluence. DLC formation with large sp(3) contents could be dem onstrated without substrate heating. Vickers hardness values and measu rements on the electron emissivity of the films are strongly correlate d to the sp(3) content and the preparation method of the films. (C) 19 98 Elsevier Science S.A.