This paper presents an investigation of the thermoelectric performance of DLC films deposited on glass substrates using RF plasma CVD method. The respective thermoelectric performances of Si-doped DLC film and non-Si doped DLC film were evaluated and compared. The DLC films showed a Seebeck effect, and they had p-type semiconductor characteristics.The values of DLC films’ Seebeck coefficients were 1/5 - 1/100 compared to those of the conventional thermoelectric materials. At temperatures of 80-200°C, the Seebeck coefficients of Si-doped DLC and non-doped DLC were almost identical. The resistivity value of DLC films decreased exponentially with increasing temperature. Furthermore, the DLC film values were much larger than those of conventional thermoelectric materials: 105 to 1010 times larger. The thermal conductivity of DLC films was about one-half that of conventional thermoelectric materials at room temperature. The results presented above suggest that reducing DLC film resistivity through control of deposition conditions, doped element composition, and other means must be examined to raise the thermoelectric performance of DLC film.
The influence of surface oxide films on anodic oxidation process in an organic electrolyte was investigated from the perspective of the breakdown voltage (Ebd). Composites of anodic oxide films were analyzed using X-ray photoelectron spectroscopy (XPS). Pre-oxidized anodic oxide film at 15 V drastically increased Ebd from 26 V to 63 V in organic electrolyte (1M LiBF4/ethylene carbonate : diethyl carbonate (1 : 1 v/v%)). Furthermore, XPS analysis of the anodic oxide film structure revealed AlF3/AlOx/2F3−x/Al. The rise in Ebd would be explained by the change in the unevenness of anodic oxide film.