Non-ohmic effects in the electronic transport in tungsten- and silicon-containing diamond-like films

Amorphous carbon diamond-like films containing tungsten and silicon in a wide range of metal concentrations (0–60 at. %) were prepared using chemical vapor deposition. Data on the electron transport are presented. The addition of metal atoms allows the electrical resistivity to be changed from 1014–1016 Ω cm down to (2–4) × 10−4 Ω cm in a controlled way. Depending on the tungsten concentration, there are two regimes of electronic conduction: dielectric and metallic. In both regimes non-Ohmic effects were observed. In the insulator-rich region, at room temperature the electric conductivity is in agreement with the Poole-Frenkel model and tends to be activationless following the Shklovskii mechanism at low temperatures. In the metal-rich region, evidence of superconductivity is observed. At temperatures below Tc quasi-reentrant peaks to the resistive state are revealed. The non-Ohmic dependences of the resistivity vs. transport current across the films in the superconducting response are presented and discussed.