Raman spectroscopy analysis of the chemical structure of diamond-like carbon films deposited via high-frequency inclusion high-power impulse magnetron sputtering

Aiming to develop a new high-power impulse magnetron sputtering (HiPIMS) method to further improve the functionality of thin films, we previously designed a high-frequency inclusion HiPIMS (HF-HiPIMS) power supply for obtaining high-performance diamond-like carbon (DLC) films. Herein, the chemical structure of DLC films deposited via HF-HiPIMS was analyzed using Raman spectroscopy. First, the peak positions were fixed, and the number of fitting parameters was reduced by conducting a waveform separation of the initial Raman spectrum using a differential spectrum method. Next, the Raman spectra of the DLC films subjected to five-peak separation and two-peak separation analyses were compared, and the limitations of the two-peak separation analysis are discussed. Furthermore, the relation between the Raman parameters of the five-peak separation analysis and film properties suggested that Raman spectroscopy could be used to estimate the sp3 C-C/(sp3 C-C + sp2 C=C) ratio.