Nitrogenation of boron doped diamond: Comparison of an electrochemical treatment in liquid ammonia and a NH3/N2 plasma

In the present work, two different nitrogenation of diamond surface were studied onto moderately doped BDD samples (10¹⁹ at cm^? 3). The effects of an electrochemical treatment in liquid ammonia have been compared to those produced by NH₃/N₂ plasma. The evolution of surface terminations from “CH” to “CN” has been studied by XPS analyses for both nitrogenation methods. Angle contact measurements complete this work, estimating the effect of such treatments on BDD wettability properties. Finally, cyclic voltammetry in presence of redox systems have been carried out to evidence the impact of “CN” bonds on BDD electrochemical behavior. In both cases the formation of “CN” terminations was evidenced by XPS analyses. Physico-chemical properties of BDD electrodes, deduced from contact angle and electrochemical measurements, were strongly modified according the process. The galvanostatic treatment in liquid ammonia led to a more hydrophobic diamond surface and an improvement of the charge transfer with Ce^4+/3+ redox couple, while a more hydrophilic surface and a notable decrease of the electrochemical response were generated by NH₃/N₂ plasma treatment.