Characterization of sp³ bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy

This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2kV and a power supply system equipped with 25/50μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp³/sp² bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp³ bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp³/sp² ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp³ phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed.