First principles study of structural, elastic, mechanical and electronic properties of nitrogen-doped cubic diamond

We report the structural, elastic, mechanical and electronic properties of nitrogen (N)-doped cubic diamond up to 25%N doping concentrations in the steps of 5%N dopant. Our calculations were performed with the generalized gradient approximation functional of density functional theory with the Perdew–Burke–Ernzerhof exchange–correlation energy through virtual crystal approximation. Cubic diamond shows a structural stability up to 15%N doping and it becomes instable above this dopant concentration. The changes for the typical cubic elastic constants, bulk, shear and Young’s moduli, Poisson ratio, anisotropy, Pugh ratio, Kleinman parameter and electronic band structures of cubic diamond vs. applied doping percentages were also evaluated. The obtained results for these parameters were found to be strictly dependent on the dopant concentration. Although cubic diamond is a well-known insulator, it displays a metallic character even under the doping of 5%N and keeps this trend for higher doping concentrations.