Raman Spectroscopy of DLC/a‐Si Bilayer Film Prepared by Pulsed Filtered Cathodic Arc

DLC/a‐Si bilayer film was deposited on germanium substrate. The a‐Si layer, a seed layer, was firstly deposited on the substrate using DC magnetron sputtering and DLC layer was then deposited on the a‐Si layer using pulsed filtered cathodic arc method. The bilayer films were deposited with different DLC/a‐Si thickness ratios, including 2/2, 2/6, 4/4, 6/2, and 9/6. The effect of DLC/a‐Si thickness ratios on the sp3 content of DLC was analyzed by Raman spectroscopy. The results show that a‐Si layer has no effect on the structure of DLC film. Furthermore, the upper shift in G wavenumber and the decrease in ID/IG inform that sp3 content of the film is directly proportional to DLC thickness. The plot modified from the three‐stage model informed that the structural characteristics of DLC/a‐Si bilayer films are located close to the tetrahedral amorphous carbon. This information may be important for analyzing and developing bilayer protective films for future hard disk drive.