Effects of nitrogen doping in amorphous carbon layers on the diffusion of fluorine atoms: A first-principles study

We investigated the effects of nitrogen doping in amorphous carbon layers on the diffusion of fluorine atoms based on density functional theory calculations. For N doping at both substitutional and interstitial sites, the F atom binds to the surrounding C atoms rather than the N atom during structural relaxation due to the electrostatic repulsion between N and F atoms. Furthermore, the diffusion barriers associated with the F atom passing by the N atom are extremely large (5.19 eV for substitutional N doping and 4.77 eV for interstitial N doping), primarily due to the electrostatic repulsion originating from the strong electronegativities of both atoms. The results clearly show that N doping increases the diffusion barrier of the F atom, thereby suppressing the diffusion of the F atom. The findings provide information about the role of N doping in amorphous carbon layers and yield insights for improving the fabrication processes of future integrated semiconductor devices.