Conduction mechanism in molybdenum-containing diamond-like carbon deposited using electron cyclotron resonance chemical vapor deposition

The conduction mechanism of molybdenum-containing (Mo) diamond-like carbon films deposited using electron cyclotron resonance chemical vapor deposition was investigated. It is found that there is a conductivity turning point at around 115 K, above which the conductivity is strongly temperature dependent. This indicates that two types of conduction mechanisms, thermal activation and tunneling coexist in the films, and they dominate the conduction behavior in the high and low temperature regimes, respectively. Within the temperature range investigated, the Poole-Frenkel effect is to be expected for thermal activation. However, due to the low concentration of Mo in the films, this effect was not observable. Tunneling is thought to occur between the Mo clusters or the sp(2) clusters. A conductivity model, based on the thermal activation and tunneling, is proposed, and showed good agreement with the results obtained at low field. The conduction behavior at high field is also discussed and some possible mechanisms are proposed. (C) 2000 American Institute of Physics. [S0021-8979(00)04620-X].