Characterization of diamond-like carbon films prepared using various source gases by plasma-based ion implantation and deposition

Diamond-like carbon (DLC) films are prepared by bipolar-type plasma-based ion implantation and deposition (PBIID) using the combination of toluene (C7H8), tetramethylsilane (TMS: Si(CH3)4) and nitrogen (N2) as a source gas. The characteristics and mechanical properties of the films are examined by Raman spectroscopy and nanoindentation measurement, respectively. The film composition is evaluated by X-ray photoelectron spectroscopy (XPS). Raman analysis reveals that polymer-like structure is formed and increases with increasing Si content. The hardness and Young's modulus decrease with increasing Si content. The ratio of Si to C (Si:C) in the films is almost equal to that in the source gases. The addition of N2 together with TMS causes a slight increase of sp2 ring clusters and improvement of the mechanical properties probably due to the formation of SiN bonds. Moreover, the Si:C ratio in the films is enhanced by the N2 addition.