Electrochemical behaviour of a-C:N:H films

Electrochemical impedance in H2SO4 solutions and the kinetics of redox reactions in the Fe(CN)63−/4− system were studied in amorphous nitrogenated diamond-like carbon thin-film electrodes. The films were fabricated on p- and i-type silicon and quartz substrates, using direct ion beam deposition from an RF inductively coupled N2+CH4 plasma source. The films were characterized by optical and electrical measurements. Parameters of point defects (trapping centres) were measured by deep level transient spectroscopy techniques. The increase in the N2/CH4 ratio in the gas mixture leads to a decrease in the electrical resistivity and optical bandgap of the films from 3×1010 to 5×106 Ω cm and from 1.3 to 0.6 eV, respectively. Simultaneously, the concentration of electrically active point defects increased and the charge transfer at the a-C:N:H film ∣ redox electrolyte interface was significantly facilitated.