Electrical Conduction Properties of Hydrogenated Amorphous Carbon Films with Different Structures

Abstract

Hydrogenated amorphous carbon (a-C:H) films have optical and electrical properties that vary widely depending on deposition conditions; however, the electrical conduction mechanism, which is dependent on the film structure, has not yet been fully revealed. To understand the relationship between the film structure and electrical conduction mechanism, three types of a-C:H films were prepared and their film structures and electrical properties were evaluated. The sp2/(sp2 + sp3) ratios were measured by a near-edge X-ray absorption fine structure technique. From the conductivity–temperature relationship, variable-range hopping (VRH) conduction was shown to be the dominant conduction mechanism at low temperatures, and the electrical conduction mechanism changed at a transition temperature from VRH conduction to thermally activated band conduction. On the basis of structural analyses, a model of the microstructure of a-C:H that consists of sp2 and sp3-bonded carbon clusters, hydrogen atoms and dangling bonds was built. Furthermore, it is explained how several electrical conduction parameters are affected by the carrier transportation path among the clusters.

Unlocking the Potential of Wood Residues for Producing Screen-Printed Electrochemical Sensors

“…With the slow kinetics of its thermal decomposition and a higher pyrolytic temperature, the formation of sp 2 structure could be favored . Graphite-like sp 2 bonds improve the electrical transport properties of the material, , resulting in an enhanced electrochemical performance. , Indeed, the electrodes prepared from the wood wastes with the lowest hemicellulose content show the best electrochemical response considering the measurements carried out with the representative redox species shown above. The K app 0 values obtained with the CPE_C c (Table ) are almost two times larger than those obtained with the commercial graphite powder, which were 220 ± 60 × 10 –4 cm s –1 for ferrocene and 15 ± 3 × 10 –4 cm s –1 for ferricyanide.…”

“…45 With the slow kinetics of its thermal decomposition and a higher pyrolytic temperature, the formation of sp 2 structure could be favored. 18 Graphite-like sp 2 bonds improve the electrical transport properties of the material, 46,47 resulting in an enhanced electrochemical performance. 42,48 Indeed, the electrodes prepared from the wood wastes with the lowest hemicellulose content show the best electrochemical response considering the measurements carried out with the representative redox species shown above.…”