Adsorption and migration behaviours of Nb-C atoms on clean diamond (001) surface: A first principles study

Adsorption and migration behaviours of Nb-C atoms on a clean diamond (001) surface were investigated using first principles methods based on density functional theory to develop a new kind of diamond composition film. Firstly, the adsorption and minimum migration energies of a single Nb atom on a surface were calculated to obtain the migration activation energy. Configuration evolutions of two atoms of 1Nb1C and three atoms of 2C1Nb were then studied to determine the effect of the Nb addition. Migrations of a single Nb atom on the clean diamond (001) surface along a dimer row and along a dimer chain were found to have energy barriers of 2.008 and 2.099 eV, respectively. The barrier was smaller than the barrier of a single carbon atom migrating along a dimer chain. Thus, the migration of the Nb atom is easier than that of the carbon atom. Besides, comparison of the configuration evolution activation energy of 2C1Nb three atoms with that of 2C dimer showed the effect of adding Nb on promoting 2C dimer migration. (C) 2016 Elsevier B.V. All rights reserved.