Microstructure and electrochemical properties of nitrogen-doped DLC films deposited by PECVD technique

Nitrogen-doped diamond-like carbon (N-DLC) films were synthesized by glow discharge plasma enhanced chemical vapor deposition (PECVD) using a hybrid ion beam system. The influence of nitrogen incorporation on the microstructure and electrochemical properties of N-DLC films was investigated by scanning probe microscopy, Raman spectroscopy, X-ray photoemission spectroscopy and cycle voltammetry. Regardless of the deposition parameters, the surface of all the deposited films is very smooth. Raman spectra show that ID/IG increases from 0.6 to 1.04 with the substrate bias voltage increases. XPS results identify that carbon is bonded with nitrogen and the substrate bias makes no distinct contribution to the N content in the films, even the N-DLC film at bias of −550 V has the lowest N-O bonds concentration and the highest C-N bonds concentration. The film electrodes show the wide potential windows range over 4 V, lower background currents in strong acid media. At the bias of −550 V, the N-DLC film electrode not only exhibits the ΔEp at 209 mV and Ipox/Ipred at 0.8778 in K3Fe(CN)6 solution, respectively, but also illustrates a nearly reversible electrode reaction. The mechanism of electroproperties is discussed in terms of the atomic bond structures and diffusion process.