Abstract
This thesis mainly focuses on the influence of precursor gases and / or the applied negative dc bias for the synthesis of carbon related materials by the PECVD, including MPECVD and ECR - CVD. This research started with an investigation of the atomic scale structure of the DLC films prepared by H2 and Ar as dilute gases under high methane condition (□5%). Graphite and diamond or silicon carbide (SiC) clusters were observed in the DLC films by HRTEM. The dispersion of diamond and SiC nano - clusters improves the film quality in terms of crystallinity and hardness of the DLC coating significantly. Crystalline carbon nitrides have been successfully deposited on silicon substrate over an intermediate layer of Si3N4 formed by chemical conversion of the silicon by MPECVD. The crystalline carbon nitride compounds were characterized by XRD and XPS, and compared to □ - and □ - Si3N4 Amorphous carbon nitride films have also been synthesized on silicon by using the ECR - CVD system in a mixture of C2H2, N2 and Ar. Excess argon together with he application of dc bias can increase the ratio of nitrogen to carbon in the film up to 41% as determined by XPS. XPS also indicated that there is an interlayer, silicon nitride and silicon carbide mixture or a tenary alloy SiCxNy, between amorphous carbon nitride and Si. FTIR spectrum shows an absorption band between 1000 and 1700 cm-1, which proves the incorporation of nitrogen atoms into the amorphous network of carbon. The plasma chemistry was also explored by OES to investigate the active chemical species, e. g. CN, H2 N2 and Ar etc., involving in the formation of carbon nitride. In this connection, it is possible to constitute a new structure for the electric, electronic, optical and magnetic applications. Vertically aligned carbon nitride nanotubes with a uniform diameter of about 250 nm on a porous anodic alumina membrane as a template have been synthesized for the first time by using ECR - CVD system with a negative dc bias applied on the substrate in a mixture of C2H2 and N2. It is also possible to control the aspect ratio and the wall thickness of these nanotubes as verified by FESEM experiments. AES analysis shows the chemical composition (Al, O, C and N ) of the specimen and the same sesult was also confirmed by XPS measurements.