Electrochemical properties of amorphous nitrogen-containing hydrogenated diamondlike-carbon films

The electrochemical impedance of thin-film electrodes made of amorphous nitrogen-containing diamondlike carbon (a-C:N:H) in H2SO4 solutions and the kinetics of redox reactions on these electrodes in the Fe(CN)63-/4- system are studied. The amorphous diamondlike carbon films with an admixture of nitrogen are grown by a directed deposition from inductively coupled methane-nitrogen plasma. The films’ resistivity values determined from the ac impedance of a-C:N:H/electrolyte contact practically coincided with those determined from the current-vol.tage curves taken at the a-C:N:H/metal contact. With an increase in the nitrogen : methane ratio in the gas phase, both the electrical resistance and optical bandgap decrease from 3 x 1010 to 5 x 106 ohm cm and from 1.3 to 0.6 eV, respectively. Simultaneously, the concentration of electrically active point-defect centers in a-C:N:H increases significantly and the reaction in the Fe(CN)63-/4- system is facilitated.