Effects of hydrogen flux and pressure on the structural properties of PECVD-synthesized carbon thin films

This study reports the synthesis of hydrogenated amorphous carbon thin films (a-C:H) on the glass and Cu substrates. For this purpose, plasma-enhanced chemical vapor deposition technique at radio-frequency (RF-PECVD) was performed, using methane (CH₄) gas as a precursor and hydrogen (H₂) gas. The major advantages of this technique are large-area processing and ability to fabricate films ranging from insulating diamond to metallic graphite. The properties of films are influenced by the deposition condition. So, this is required to investigate the correlation between the film characterization and the deposition condition. After the deposition process, the influence of H₂ gas flow rate and chamber pressure on the structure of the films were evaluated by Raman spectroscopy. Moreover, the surface morphology and thickness of the films were investigated by using field emission scanning electron microscopy (FE-SEM) and profilometry, respectively. It is found that both pressure and hydrogen gas flow rate have considerable influence on the films stability. Also, the thickness of the carbon films clearly decrease as H₂ gas flow rate increases.