Nitrogen implantation into diamond-like carbon films prepared by bipolar-type plasma based ion implantation

Different type of diamond-like carbon (DLC) films, such as electrically insulating and conductive ones are, prepared by bipolar-type plasma based ion implantation. They are implanted using 80 keV N2+ ions at a dose of 5×1016N2+/cm2. And the changes in surface morphology and the microstructure are examined by atomic force microscopy (AFM) and Raman measurements. Elementary composition of the samples is checked by Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA). The results of RBS measurements indicate that the areal density of N is approximately 1×1017atoms/cm2 in the samples. The results of ERDA measurements also show that H decreases in concentration near the surface region of the films. Smooth and rough granular surfaces are observed for insulating and conductive DLC films, respectively. The results of Raman measurements reveal that the conductive DLC films are mainly composed of graphite-like structure. After N implantation, the surface morphology and the microstructure of the insulating DLC films are not changed significantly. However, for the conductive DLC films, the surfaces become smoothening due to amorphization by N implantation. In the case of the Si containing conductive DLC films, the surface smoothening effect is weakened.